APL Field Switch with Automatic Protocol Detection

Abstract

A protocol detection circuit for detecting a field device protocol of a field device attached to a channel having data lines is sequentially connected to the data lines by a controller that communicates with the field device via the protocol detection circuit. After completing protocol detection, the protocol detection circuit is disconnected from the field device. The channel may be one of several channels, and the controller may also connect and disconnect the protocol detection circuit to one channel, so that the protocol detection circuit can be used on any channel. After the protocol of the field device is identified, a protocol adapter can be inserted into the channel to enable data conversion between the field device protocol and another protocol used by the channel for data transmission.

Description

Technical Field

[0001] This application claims the benefit of the priority and filing dates of U.S. Patent Application No. 63 / 152,435, titled "APL Field Switch with Automatic Protocol Detection," filed on February 23, 2021, with Attorney Docket No. 14-1383-P, and U.S. Patent Application No. 63 / 152,438, titled "APL Field Switch with Integrated Protocol Detection," filed on February 23, 2021, with Attorney Docket No. 14-1384-P, the priority applications of which are pending as of the filing date of this application and are hereby incorporated by reference as if fully set forth herein.

[0002] This disclosure generally relates to field switches, particularly APL field switches, for use in process control networks.

Background Art

[0003] The Ethernet Advanced Physical Layer (APL) specification is based on the industry standard (IEEE 802.3cg) for the physical layer of Ethernet-based two-wire process control networks. APL networks enable a full-duplex data rate of up to 10 megabits per second (Mbps) to and from APL-compatible field devices for long-distance transmission. APL field devices include sensors, actuators, etc., required for the operation of advanced process control networks.

[0004] APL field devices are typically connected to an APL field switch. The APL field switch typically has 8 to 24 channels that connect to APL field devices. The channels of the APL field switch transfer power to the connected APL field devices and transfer data between the APL field devices and the process control network. An example of a commercially available 24-channel APL field switch is the FIELDCONNEX sold by Pepperl+Fuchs GmbH in Mannheim, Germany. (R) It is the ARS11-B2-IC24-1 APL field switch.

[0005] Due to the advantages provided by the APL network, many industries are installing APL networks (including APL field switches) when building new process control infrastructure. However, APL field devices are not readily available as dependencies. When building new infrastructure, it is necessary to rely at least partially on conventional non-APL field devices. A policy of upgrading from conventional field devices to APL field devices is desirable. While allowing the replacement of conventional field devices with APL field devices when they become available, the policy should enable conventional field devices to be connected to an APL field switch.

[0006] Industries using existing process control networks often have to expand their network infrastructure. Although investment in additional conventional field devices may not be desirable, considering the cost of removing field devices in hard-to-reach locations that are still in good operating condition, replacing conventional field devices with APL field devices may also not be desirable. An expansion that allows the simultaneous use of APL field devices and conventional field devices may be a desirable solution that still provides a policy for upgrading from conventional field devices to APL field devices.

[0007] Therefore, an APL field switch having channels that enable connection of both APL field devices and conventional non-APL field devices is needed. However, conventional non-APL field devices do not use the same field device protocol (data and power specifications) as APL field devices. If a conventional field device can operate in an APL process control network while being connected to the network via an APL field switch, it is necessary for the APL field switch to perform protocol conversion between the APL protocol and the non-APL protocol.

[0008] One solution is an APL field switch that includes on-board hardware and software that support any conventional non-APL protocol on any channel. However, there are many conventional protocols. This solution is prohibitively costly, and customers would have to pay for hardware that they may never use.

[0009] Another solution is an APL field switch that includes on-board hardware and software that support a small subset of non-APL protocols. However, this severely limits the number of conventional field devices that can be attached to the APL field switch.

[0010] Yet another solution is an APL field switch that includes on-board hardware and software on a few fixed channels. However, this makes it difficult to order the correct number of APL field devices or APL field devices with the correct number of fixed channels. The likelihood of installation errors, where field devices (conventional or APL) are attached to the wrong channel, also increases.

[0011] A further alternative solution is an APL field switch that supports only one non-APL protocol. For example, FIELDCONNEX (R) The ARS11-B2-IC24-1 APL field switch can be used with PROFIBUS·PA· field devices. However, this does not provide the flexibility required by many new and existing process control infrastructures.

SUMMARY OF THE INVENTION

PROBLEM TO BE SOLVED BY THE INVENTION

[0012] Therefore, there is a need for an APL field switch that enables conventional non-APL field devices having many different conventional field device protocols to be securely attached to any channel of the APL field switch in a cost-effective manner.

MEANS FOR SOLVING THE PROBLEM

[0013] Disclosed is an APL field switch that enables conventional non-APL field devices having many different conventional field device protocols to be securely attached to any channel of the APL field switch in a cost-effective manner.

[0014] The solution is to place the protocol conversion in a pluggable protocol adapter inserted into the channels of the APL field device to convert between the APL protocol and the attached conventional field device protocol. Various protocol adapters can be installed in any of the channels of the APL field device.

[0015] A wide range of protocol adapters that support a wide range of conventional field device protocols are available, providing the flexibility required by many new and existing process control infrastructures.

[0016] By purchasing protocol adapters based on customer needs, the customer only incurs costs for and pays only for the necessary protocols for conventional field devices connected to the APL field switch. Some protocols require expensive support circuitry, and providing such circuitry for each channel makes the purchase of the APL field switch expensive whether or not the customer will use the circuitry. With protocol adapters, the customer does not purchase expensive circuitry if not needed.

[0017] Protocol adapters enable the customer to easily make changes to the network. Protocol adapters can be replaced when changing from one conventional field device to another or whenever infrastructure requirements change.

[0018] The APL field switch according to the present disclosure includes protocol adapter connectors on each channel. Plugging a protocol adapter into a protocol adapter connector arranges the protocol adapter in series with the channel. The protocol adapter can transfer power through the protocol adapter to power the attached field device and to convert the data format between the APL data format and the conventional data format for network communication. The protocol adapter can include expensive conventional circuitry for high-speed data communication with the attached field device in a conventional data format.

[0019] The installer can place conventional field devices on any available channel of the APL field switch and install a protocol adapter compatible with that channel. Channels connected to APL field devices do not require a protocol adapter as the channel itself is compatible with the APL protocol. If all connected field devices are APL field devices, there is no need to purchase a protocol adapter. And the APL field devices provide the assurance that they can be connected to conventional field devices if needed, but if not, there is no cost incurred to obtain that functionality by using a protocol adapter.

[0020] It may be difficult to identify the protocol used by a conventional field device, and thus it may be difficult to know which protocol adapter to use for a given conventional field device.

[0021] Also disclosed herein is a protocol detection circuit that enables automatic detection of the protocol used by a field device (whether an APL field device or a conventional field device). Each protocol detection circuit is specialized to detect a respective field device protocol or a family of compatible protocols.

[0022] After attempting each protection detection circuit, the controller sequentially connects to the field devices to which each protocol detection circuit is attached and communicates with the field devices until the protocol is detected or until the controller fails to detect the protocol. Since communication with the field device during protocol detection does not have to be high-speed communication, the protocol detection circuit can eliminate the expensive circuitry required for high-speed data communication.

[0023] Since the protocol of the attached field device is unknown, it is important to limit the first power transmission to a safe current or amperage. A safe current is a current that is low enough that the terminator resistance of the field device does not consume power exceeding its maximum rating. Each channel includes a selectably adjustable current limiting device connected to and controlled by a controller. The controller first sets the current limiting device to the safe current state before initiating protocol detection. When the detected protocol permits higher power transmission, the controller sets the current limiting device to the corresponding current state.

[0024] When protocol detection is complete, the name of the detected protocol or the failure of protocol detection is displayed to the user. The user selects a protocol adapter for use based on the detected protocol.

[0025] In an embodiment of the disclosed APL field switch, the APL field switch includes a protocol detection circuit, a controller, and a selectable current limiting device in each channel. When a field device is first attached to a channel, the controller sets the channel's current limiting device to the safe current state and initiates protocol detection. If the controller detects whether the field device is an APL field device, it connects to the channel itself. The controller sequentially connects the protocol detection circuit to the channel to connect the protocol detection circuit to the attached field device.

[0026] When a channel is attached to an APL field device, the controller can be configured to enable dynamic power allocation of the channel to a user-selectable APL power class.

[0027] A single set of protocol detection circuits can be used on any channel to which a field device is attached. It is not necessary to provide multiple copies of the set for each channel. The hardware cost of the APL field switch is reduced while still allowing conventional field devices to be attached to any channel of the APL field switch.

[0028] In still other embodiments of the disclosed APL field switch, the APL field switch does not include a protocol detection circuit. Instead, a portable hand-held protocol detection tool can be used to automatically detect the protocol of a field device attached to the protocol detection tool. The protocol detection tool includes an APL channel, a protocol detection circuit, and a controller. As described above, the field device is attached to the APL channel and the controller initiates and performs protocol detection. The tool can be battery-powered or driven via an AC adapter.

[0029] Other objects and features of the present disclosure will become apparent when considered in conjunction with the accompanying drawings, particularly when illustrated in one or more exemplary embodiments as the description proceeds.

Brief Description of the Drawings

[0030]

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MODE FOR CARRYING OUT THE INVENTION

[0031] FIG. 1 illustrates a process control network 10 consisting of a 10 Mbps Ethernet-APL process control network 12 and a 100 Mbps industrial Ethernet process control network 14.

[0032] The APL-Ethernet process control network 12 complies with the Ethernet Advanced Physical Layer (APL) specification. The APL-Ethernet network 12 uses a two-wire trunk cable and a two-wire spur cable for simultaneous data transmission and power transmission via two wires. The trunk and spur of the APL-Ethernet process control network 12 are shown by solid lines in FIG. 1.

[0033] The illustrated industrial Ethernet process control network 14 is an Ethernet / IP (Ethernet industrial protocol network). The industrial Ethernet network 14 uses Ethernet cables from standard Ethernet CAT5 and later (referred to herein as "standard Ethernet cables") and related hardware commonly used in business Ethernet LAN networks. The standard Ethernet cable is shown by a dashed line in FIG. 1.

[0034] The process control network 10 includes a back end having an engineering station 16, an operation station 18, a process controller 20, and a back-end non-APL Ethernet switch 22. The back-end stations, process controllers, and Ethernet switches are connected by Ethernet cables of CAT5 or later for high-speed Ethernet communication (100 Mbps or more).

[0035] The industrial Ethernet network 14 includes a non-APL Ethernet switch 24 connected to the back-end Ethernet switch 22 by an Ethernet cable of CAT5 or later. The industrial Ethernet switch 24 is powered by an auxiliary power supply represented by an arrow 25. The industrial Ethernet switch 24 is connected to a non-APL field device 26a and a non-APL field device 26b by an Ethernet cable of CAT5 or later. The field devices 26a and 26b are powered by an auxiliary power supply without going through the network. The back end can communicate with the field devices 26a and 26b via the back-end Ethernet switch 22 and the industrial Ethernet switch 24.

[0036] The APL-Ethernet network 12 includes an APL power switch 26, and the APL power switch 26 is connected to an APL trunk 28 that extends from the APL power switch to a downstream APL field switch 30 and further downstream to an APL field switch 32. The APL power switch 26 receives power from an auxiliary DC power supply represented by an arrow 34. The APL power switch 26 injects power into the APL trunk for simultaneous transmission of power and data through the trunk.

[0037] The APL power switch 26 is connected via a cable of standard Ethernet CAT5 or later to the backend Ethernet switch 22 for data transmission. The APL power switch 26 converts between 100Mbps Ethernet transmitted via a standard Ethernet cable and 10Mbps Ethernet transmitted via an APL-Ethernet two-wire cable for data communication between the APL-Ethernet network 12 and the backend Ethernet switch 22.

[0038] The APL field switch 30 is shown connected to the network trunk 28 and can transmit the power received from the network trunk to the field devices attached to the APL field switch. The APL field switch 30 is connected to the field devices 36a, 36b, and 36c by respective two-wire APL-compatible spurs extending from the ports of the APL field switch. The APL field switch 30 can transmit data to and from the field devices 36 and supply the power received via the network trunk 28 to the field devices 36.

[0039] The APL field switch 32 is shown connected to an auxiliary power source represented by the arrow 38. The APL field switch 32 is not powered from the trunk 28 but transmits and receives data via the APL trunk 28. The APL field switch 32 as shown in FIG. 1 is connected to the field devices 40a and 40b by respective two-wire APL-compatible spurs extending from the ports of the APL field switch. The APL field switch 32 can transmit data to and from the field devices 40 and supply the power received via the auxiliary power source 38 to the field devices 40.

[0040] The field devices 26, 36, 40 are sensors, actuators, etc. that are compatible with the field switches to which they are connected. The field devices are configured to output sensor data, operating status, command confirmation, diagnostics, and other outgoing network communications required for the operation of the process control network 10, and / or to receive commands, data requests, and other incoming network communications required for the operation of the process control network 10.

[0041] Since the two APL field switches shown in FIG. 1 are identical, only the APL field switch 30 will be described in detail.

[0042] The APL field switch 30 is connected to the APL field device 36a, as well as to the conventional non-APL field devices 36b and 36c. The APL field switch 30 is configured to operably connect to the APL field device by attaching an APL spur from the APL field switch to the field device. The APL field switch 30 has an internal protocol detection circuit (shown and described in detail below) that includes a controller that detects whether an APL field device is attached to the field switch.

[0043] When an APL field device is detected, no further user configuration is required. The port transfers data to and from the APL field device in accordance with the APL specification and supplies power to the APL field device via the port.

[0044] When the protocol detection controller detects that the attached field device is not an APL field device, the controller sequentially connects the field device to several respective protocol detection circuits that can each identify their respective non-APL network protocols as used by non-APL field devices. The protocol detection controller notifies the user of the detected non-APL protocol or the failure of protocol detection.

[0045] When a non-APL protocol is detected, the user utilizes a protocol adapter that is compatible with the detected protocol. The protocol adapter is arranged in series with the port. The protocol adapter converts data between the APL data protocol and the data protocol of the field device in order to enable data transmission between the field device and the network trunk or other data terminals of the APL field switch.

[0046] The protocol adapter can also transmit the power received by the APL field switch 30 through the protocol adapter and transmit it to the port for power transmission to the field device.

[0047] However, not all field device protocols are "data and power protocols" that require both data transmission and power transmission. Some field device protocols are "data-only" protocols that do not perform power transmission to the field device. The protocol adapter for a "data-only" protocol permits data transfer through the protocol adapter while not permitting power transfer through the protocol adapter.

[0048] The protocol detection circuit also incorporates a power circuit that enables the controller to selectively adjust the maximum power that can be transmitted through the port while detecting the field device protocol. The physical layer specifications of various network protocols specify various power requirements (including zero power requirements) and may specify that the field device has a termination resistor for proper network operation. The controller sets an initial current to the field device at the start of protocol detection, which prevents the resistor from consuming power beyond its maximum power rating.

[0049] Field device 36b is a PROFIBUS·PA·field device. The PROFIBUS·PA·protocol is a protocol for power and data. Other power and data protocols include, but are not limited to, the APL protocol and the Foundation·Fieldbus·protocol. Field device 36c is a MODBUS·RTU·field device. The MODBUS·RTU·protocol is a data-only protocol. Another data-only protocol is DP (Profibus·DP), but is not limited to this. The illustrated APL field switch 30 includes PROFIBUS·PA and MODBUS·RTU·protocol detection circuits. Removable PROFIBUS·PA·protocol adapters and removable MODBUS·RTU·protocol adapters are installed in the APL field switch 30 and are connected to PROFUS·PA·field device 36b and MODBUS·RTU·field device 36c, respectively.

[0050] Figure 2 schematically illustrates the components of the APL field switch 30. The APL field switch has a trunk terminal 42 for connecting the field switch to the APL trunk 28 and an external power supply terminal 44 for connecting the field switch to an auxiliary power supply (such as the auxiliary power supply 38). The illustrated APL field switch 30 also includes one or more dedicated data ports 46 that transmit data rather than power inside and outside the APL field switch 30. The dedicated data port 46 can be implemented as an Ethernet RJ45 connector, an SFP optical connector, etc. for connection to a compatible external optical or electrical data cable.

[0051] When the APL field switch is powered by an APL trunk connected to the trunk terminal 42, the trunk terminal 42 functions as a power terminal for receiving power for the APL field switch and as a data terminal for transmitting data between the APL trunk and the APL field switch. When the APL field switch is powered by an external power supply connected to the external power supply terminal 44, the external power supply terminal 44 functions as a power terminal for receiving power for the APL field switch, and the trunk terminal 42 functions as a data terminal for transmitting data between the APL trunk and the APL field switch. Each dedicated data terminal 46 functions only as a data terminal for transmitting data to and from the APL field switch 30.

[0052] The power received via the power terminals 42, 44 is received by the APL field switch 30 via the power lines 48 connected to the terminals 42, 44. The power lines 48 also transmit data to the APL field switch via the trunk terminal 42 and transmit data from the APL field switch via the trunk terminal 42. The data line 50a extends between the power line 50 and one end of the Ethernet switch 52. The data line 50a extracts the data received via the trunk terminal 42 from the power line 48, transmits the data to the Ethernet switch 52, and injects the data received from the Ethernet switch 52 into the power line 48 for transmission via the trunk terminal 42. The data line 50b extends between each data terminal 46 and one end of the Ethernet switch 52 for data transmission to and from the data terminal 46. Next, the Ethernet switch 52 has a data line represented as a data line 54 extending from the other end of the Ethernet switch for transmitting data between the Ethernet switch and a field device connected to the Ethernet switch.

[0053] The power line 48 and the data line 54 extend to N similar channels 56 that extend parallel to each other from the power line 48 and the data line 54 to their respective ports of the APL field switch 30. The channels 56 may be electrically insulated from each other and from the power line 48.

[0054] A 10BaseTIL Ethernet physical layer transceiver 58 is disposed on the data line 54 between the channel 56 and the combined power / data line 50. The transceiver 58 enables communication of Ethernet - formatted data frames between the channel 56 and the combined power / data line 50. An insulating switching power supply 60 that electrically insulates the channel 56 from the power terminal is disposed on the power line 48 before the channel 56.

[0055] FIG. 2 illustrates two of the N channels 56, and FIG. 3 is an enlarged view of channel 56. The channels 56 transmit data and power between the power line 48 and the data line 54 and the port 62. The port 62 of each channel has a port terminal 64 configured as a two-wire Ethernet-compatible port connector. In an alternative embodiment, the port terminal 64 may be configured as a screw or clamp terminal, an M12 connector, or other connector compatible with the APL specification. Various styles or types of port terminals 64 may be provided by APL field switch manufacturers, and the port 62 may include multiple types of port terminals 64 provided in parallel to enhance connection flexibility when connecting a field device to the port of an APL field switch.

[0056] The channel 56 includes a channel data line 66 which is one of the data lines 54, and a channel power line 68. The end of the channel data line 66 away from the Ethernet switch 52 is connected to and extends from the channel power line 68. The channel data line 66 extracts data transmitted via the port 62 from the channel power line 68 and injects data transmitted from the Ethernet switch 52 into the channel power line 68. The channel data line 66 includes an APL-compatible transceiver 70 that receives an Ethernet data frame from the Ethernet switch 52 and transmits the Ethernet data frame thereto.

[0057] The channel power line 68 is connected to the power line 50 and is formed as a two-wire line extending from the power line 50 to the port terminal 64. The channel data line 66 is connected to the channel power line 68 before the channel power line connects to the port terminal 64. And the port terminal 64 can transmit power from the port 62 and can transmit and receive data via the port 62.

[0058] The channel data line 66 and the channel power line 68 include conventional circuit components that enable separation and combination of power and data, intrinsic safety, overvoltage protection, insulation, etc. Transmission of power and data frames via channel 56 is conventional except that channel 56 enables automatic protocol detection of field devices, operable connection of non-APL field devices to channel port 62 using a protocol adapter, and dynamic setting of the maximum power that can be transmitted via channel 56 as will be described in more detail below.

[0059] As best shown in FIG. 3, channel 56 includes a protocol adapter connector 72 formed as an electrical connector disposed in series with channel power line 68 between channel data line 66 and port terminal 62. The protocol adapter connector is used to insert a protocol adapter (described in more detail below) into channel power line 68. Protocol adapter connector 72 has terminals 74 and 76 that connect connector 72 to the channel power line. Protocol adapter connector 72 has connector terminals 78 and 80 connected to power terminals 74, 76 respectively, which are configured to cooperate with corresponding terminals of the protocol adapter to electrically connect the protocol adapter in series with channel power line 68.

[0060] As shown in FIG. 3, protocol adapter connector 72 normally opens channel power line 68 and blocks transmission of power and data via channel 56. When an APL field device is connected to port 62, there is no need to use a protocol adapter. In such a case, a through-connector 82 formed as an electrical connector compatible with protocol adapter connector 72 is attached to protocol adapter connector 72 (see FIG. 4). Through-connector 82 provides continuity of the circuit across protocol adapter connector 72.

[0061] If the field device is initially attached to channel port 62, the pass-through connector 82 must be attached to the protocol adapter connector 72 for continuity across the protocol adapter connector 72 when the protocol of the field device is detected.

[0062] FIG. 5 is an external view of the APL field switch 30. Each port 62 has an associated open slot 84 (see FIG. 19) that provides access to the protocol adapter connector 72 connected to the port 62. When the protocol adapter is not installed in the slot (e.g., when an APL field device is connected to the port), the slot is closed by a cover 86. FIG. 5 illustrates the cover 86 closing all the slots. In the illustrated embodiment of the APL field switch, each cover 86 incorporates two conductors that form part of each pass-through connector 82 in series with the protocol adapter connector terminals 78, 80. When the cover is in place, the cover ensures electrical continuity across the protocol adapter connector 72 in the slot closed by the cover.

[0063] In other possible cover embodiments, the cover 86 itself is non-conductive but has a pass-through connector 82 connected to the cover. By closing the slot with the cover, the pass-through connector is installed on the protocol adapter connector 72.

[0064] Referring back to FIG. 2, the APL field switch 30 includes a protocol detection module 88 that includes a protocol detection circuit (shown in more detail in FIG. 6) that enables automatic protocol detection of a field device newly attached to the port. The protocol detection circuit includes a controller 90 that operates the protocol detection circuit to detect and identify the field device protocol. The controller 90 includes a microprocessor or central processing unit (CPU) 92 that issues commands to the protocol detection circuit and receives data from the protocol detection circuit. The CPU 92 has read / write access to an application software consisting of executable instructions 96 executable by the CPU 92 to perform the controller function, and a storage or memory 94 that holds data processed by its function. The memory 94 may be a persistent memory such as an EEROM memory or other type of non-volatile memory used in an embedded system, and may include volatile memory. A battery power supply may be provided to maintain the volatile memory in the event of a power outage.

[0065] In possible embodiments, the controller 90 may be implemented as a system-on-chip (SoC) that may include a microcontroller along with other peripheral devices necessary to perform the controller function.

[0066] The controller 90 is disposed on the data line 54 between the transceiver 58 and the channel 56. The controller 90 can read data from the data line 54 and can transmit data to the data line 54.

[0067] The controller 90 is also connected to a communication line 98 that is used to notify the user of the detected field device protocol (or the failure to detect the field device protocol). The display 100 indicates notifying the user of the detected field device protocol. The display 100 may be disposed on top of the APL field switch 30 itself or may be separate from the APL field switch. The communication line 98 may take one or more forms of connection, such as a Bluetooth wireless connection to a smartphone or the like, a wired connection such as a serial USB cable or an Ethernet cable connected to the controller, and / or a connection via a data line 54 through the APL data terminals 42, 48. The controller 90 may be configured to be regarded as a field device on the process control network for communicating via the process control network.

[0068] The protocol detection circuit 88 further includes several respective protocol detection circuits 102 connected to the controller 90. The illustrated APL field switch 30 has two protocol detection circuits, but the manufacturer may also provide an APL field switch having only one protocol detection circuit 102 or an APL field switch having three or more protocol detection circuits 102, depending on what types of conventional non-APL field devices are supported by the APL field switch.

[0069] Each protocol detection circuit 102 is configured to detect each set of one or more compatible non-APL field device protocols. For example, protocol detection 102a is configured to detect the "data only" protocol of DP / MODBUS·RTU·field devices. Protocol detection circuit 102b is configured to detect the "power and data" protocol of PROFIBUS·PA / FOUNDATION·FIELDBUS. The APL field switch 30 can include a set of one or more data-only protocol detection circuits, a set of one or more power and data protocol detection circuits, or each set of a data-only protocol detection circuit and a power and data protocol detection circuit.

[0070] The protocol detection circuit 102 can be selectively connected to each channel 56 for protocol detection of field devices attached to the channel port, as will be described in more detail below. In this way, individual non-APL protocol detection circuits 102 can be used on all channels 56 without the need for a dedicated protocol detection circuit for each channel.

[0071] Next, the protocol detection circuit 102 will be described. The protocol detection circuit 102 includes a data line 104 and a transceiver 106 connected to the data line 104 that complies with the physical layer of the protocol associated with the protocol detection circuit. When the controller 90 attempts to determine whether a field device uses the device protocol associated with the protocol detection circuit, the controller attempts to communicate with the field device using that protocol. The controller attempts to communicate using the transceiver 106, and if successful, transmits data to the field device via the transceiver and then transmits the data. For example, a Fieldbus field device does not respond until it receives a command. The controller 90 transmits a command to the field device to initiate communication, and when it receives a response from the field device, it can determine whether the field device uses that protocol.

[0072] In the illustrated embodiment, when a field device is first attached to the channel port 62, the controller 90 first determines whether the field device is an APL field device. If the controller determines that the field device is not an APL field device, the controller sequentially connects the field device to the protocol detection circuit 102 until the field device protocol is identified or the controller attempts detection by all protocol detection circuits 102. The controller may repeat only via the data-only protocol circuit if it determines that the field device is a data-only field device. Similarly, if the controller identifies the field device as a power and data field device, it may repeat only via the power and data protocol circuit.

[0073] As shown in FIG. 6, the data lines 104 of the protocol detection circuit 102 are connected in parallel to a common data line 108. A relay 110 is disposed on each data line 104, connected to and controlled by the controller 90. The relay 110 selectively connects the data line 104 to the common signal line 108 and disconnects the data line 104 therefrom. When the relay 110 is open, the protocol detection circuit 102 is effectively electrically isolated from other protocol detection circuits and from all channels 56.

[0074] The relay 110 of the protocol detection circuit is closed only while the protocol detection circuit 102 is being actively used by the controller 90 for protocol detection.

[0075] From the common signal line 108, respective channel protocol detection data lines 112 extend in parallel, and each channel protocol detection data line 112 is connected to a respective channel 56. FIG. 6 illustrates a channel protocol detection data line 112-1 connected to the channel data line 69 of channel 1. The other channel protocol data lines 112-2 to 112-N are similarly connected to the data lines 69 of respective channels 2 to N.

[0076] A protocol detection data relay 114, connected to and controlled by the controller 90, is disposed on each channel protocol detection data line 112. The relay 114 selectively connects the channel protocol detection data line 112 to the common signal line 108 and disconnects the channel protocol detection data line 112 from the common signal line 108. When the relay 114 is open, the protocol detection data line 112 cannot be connected to any of the protocol adapters 102. In addition, the channel 56 connected to the protocol detection data line 112 is electrically isolated from other channels 56.

[0077] The channel protocol detection data relay 114 connected to channel 56 is closed only while the protocol detection circuit 102 is used to detect the device protocol of the field device attached to channel 56. By closing the protocol detection circuit relay 110, channel 56 is connected to the protocol detection circuit including relay 110.

[0078] As described above, when a field device is attached to channel port 62, the controller 90 first determines whether the field device is an APL field device. Channel 56 of the port is used as a protocol detection circuit when the controller 90 determines whether the attached field device is an APL field device. The controller 90 attempts to communicate with the field device via the data line 54 through the channel transceiver 70. FIG. 6 schematically illustrates the transceiver 70 of channel 1 connected for communication with the controller 90. It should be understood that the controller 90 can communicate with each channel transceiver 70.

[0079] Each channel 56 includes a relay 116 in the channel data line 66 connected to and controlled by the controller 90. When channel 56 is actively used to detect the device protocol of the field device attached to channel 56, the channel data relay 116 is closed for data communication between the controller 90 and the field device. Since the protocol detection circuit relay 110 and the channel protocol detection relay 114 are all open, all data communication between the controller 90 and the attached field device must pass through the channel data line 66 and the channel transceiver 70.

[0080] When the controller 90 determines that the field device attached to the channel port 62 is an APL field device, the channel data relay 116 remains closed for data communication via the closed relay 116 between the data line 54 and the channel port 62.

[0081] When a field device is first connected to the channel port 62 of channel 56, the field device is connected to the channel power line 68. Since the device protocol has not yet been determined, it is important that the current supplied to the field device at the time of connection is low enough to prevent the terminator of the field device from consuming power beyond its maximum power rating. For example, PROFIBUS·DP or MODBUS·RTU field devices have a lower maximum power rating than PA / FOUNDATION·FIELDBUS field devices. In other words, the maximum current that can flow through channel 56 at the time of connection must be limited to such an extent that the maximum power output that can be transmitted through channel 56 does not exceed the minimum safe power output that will not harm the field device attached to channel port 62.

[0082] The protocol detection circuit 88 includes each channel 56 having a selectable inline current limiting device 118 disposed on the channel power line 68. The current limiting device disposed in the circuit operates when the current exceeds a predetermined maximum current (in amperes), thereby interrupting the circuit to stop the current flow or reducing or maintaining the current in the circuit at a safe level. The current limiting device limits the maximum flow of current through the channel port 62.

[0083] Known types of selectably adjustable current limiting devices that can be adapted for use in the present disclosure are an electronic fuse (eFuse) connected to a resistor with a selectable resistance value, and a constant current limiting circuit, and a foldback current limiting circuit, and A parallel resettable fuse configuration with different ampere ratings arranged in series with a relay that selects which fuse to activate, and including, but not limited to, these.

[0084] An electronic fuse is a fully electronic selectable current limiting fuse that stops current when activated.

[0085] A constant current limiting circuit allows current to pass until a maximum current is reached. Then, the circuit reduces the voltage to prevent the current from exceeding the maximum current. FIG. 7 illustrates an exemplary constant current limiting circuit that can be adapted for use in the present disclosure.

[0086] A foldback current limiting circuit allows current to pass until a maximum current is reached. The circuit reduces the voltage and current to prevent the current from exceeding the maximum current. FIG. 8 illustrates an exemplary foldback current limiting circuit that can be adapted for use in the present disclosure (image attribution: by Mikiemike from the English version of Wikipedia, CC BY-SA 3.0, https: / / commons.wikimedia.org / w / index.php?curid=70852656).

[0087] Current limiting circuits utilize resistors to set the maximum current flowing through the circuit. By utilizing variable resistors that allow for dynamic selection of the resistance value in the design of these circuits, the maximum current flowing through the circuit, and thus the maximum power output of the circuit, can be selected by choosing the resistance value of the resistor.

[0088] Current limiting circuits can also be connected in series with a static switched driver, such as the LTC7003 driver available from Analog Devices, Inc., Wilmington, Massachusetts 01887, USA, which allows for the detection of a relatively large voltage drop.

[0089] FIG. 9 illustrates a selectable current limiting device 118 formed as a parallel fuse configuration including a positive temperature coefficient (PTC) resettable fuse that can automatically reopen after cooling. A PTC fuse that may be adapted for use in accordance with the present disclosure may be obtained from the Electronics Division of Eaton in Cleveland, Ohio, USA. Fuses 115 are each arranged in series with a relay 117 that is connected to and controlled by a controller 90. Closing one relay and holding the other relay open enables the controller 90 to selectively insert a selected one of the fuses 115 into the channel power line 68.

[0090] In the illustrated embodiment, the selectable current limiting device 118 includes an electronic fuse or eFuse. An eFuse is an example of a fully electronic selectable current limiting fuse that stops the current through channel 56 when the current exceeds a predetermined number of amperes when operating. The eFuse does not rely on heating of an in-line element and subsequent open circuit to stop the current, reacts quickly, and can be easily reset.

[0091] The eFuse is attached to a digital potentiometer having a selectable resistance value. The resistance value of the digital potentiometer sets the current limit at which the eFuse opens. Next, the maximum power that can be transmitted through channel 56 is determined by the current limit at which the eFuse opens.

[0092] The controller 90 is connected to each current limiting device 118. When a field device is first attached to the channel port 62, the controller 90 sets the maximum power output of channel 56 by setting the resistance value of the potentiometer to a value that limits the maximum channel power output to below the minimum safe power output.

[0093] FIG. 10 illustrates an embodiment of a selectable current limiting device 118 disposed on a channel power line 68. The current limiting device 118 includes an eFuse 120. The eFuse 120 is aligned with the channel power line 68 such that current flowing through the channel power line 68 must flow through the eFuse 120. The eFuse 120 enables a resistor to be connected to the eFuse 120 that sets a current limit at which the eFuse opens. Connecting a variable resistor to the eFuse 120 enables the current limit to be selectively varied based on the selected resistance value of the variable resistor.

[0094] eFuses provide many advantages for controlling current. eFuses are commercially available as integrated circuit packages from Texas Instruments, Toshiba, STMicroelectronics, and other vendors. eFuses should be selected based on amperage and voltage capacity, response speed, energy efficiency, etc.

[0095] The eFuse 120 is attached to a digital potentiometer 122 that functions to enable different current limits to be set to open the eFuse. Digital potentiometer integrated circuits are available from Analog Devices, Microchip, Texas Instruments, and other suppliers.

[0096] The illustrated digital potentiometer 122 includes a resistor ladder 124 and electronic switches 126 at each step of the ladder. During operation, one switch 126 is closed at a given time to determine the effective resistance value of the digital potentiometer (similar to the operation of the wiper of a conventional analog potentiometer).

[0097] The operating state of the set of switches 126 is controlled by a digital potentiometer control unit 128 that can receive commands from the controller 90 to set the resistance value of the digital potentiometer. Digital potentiometers with compatible control units are commercially available for connection to the controller 90 via I2C and SPI serial networks.

[0098] The digital potentiometer 122 enables selectively varying the resistance value that sets the current limit of the eFuse to open the eFuse at different maximum currents and thus different maximum power outputs. When a field device is first attached to the channel port 62, the controller 90 sets the maximum power output of channel 56 by setting the resistance value of the potentiometer 122 to a value that limits the maximum channel power output to below the minimum safe power output.

[0099] FIG. 11 illustrates an eFuse 120 having a digital potentiometer 122 set to a relatively high resistance value suitable for setting channel 56 to a lower maximum power output. The eFuse opens at a lower current flowing through the eFuse.

[0100] FIG. 12 illustrates an eFuse 120 having a digital potentiometer 122 set to a relatively low resistance value suitable for setting channel 56 to a higher maximum power output. The eFuse opens at a higher current flowing through the eFuse.

[0101] Referring back to FIG. 10, the illustrated current limiting device 118 includes a microprocessor or MCU 130 connected to the control unit 128 by the UART circuit 132. The MCU 130 communicates with the control unit 128, whereby the control unit 128 sets the desired resistance value of the digital potentiometer 122.

[0102] The MCU is connected to the controller 90 by an I2C network (not shown). The controller 90 has data applicable to a digital potentiometer 122 that enables the controller to command the MCU to set the resistance value of the potentiometer to a desired resistance value. The controller 90 can individually address each channel MCU 130, set the desired resistance value of the connected digital potentiometer 122, and thereby instruct the MCU 130 to establish the maximum power output of each channel 56.

[0103] Figure 13 illustrates a switchable resistor type digital potentiometer 122 that can be used in place of the ladder type digital potentiometer 122. The switchable resistor type digital potentiometer 122 replaces the resistor ladder 124 with several parallel resistors, each resistor being in series with its respective programmable switch. The resistance values of the resistors vary. Each switch can be selectively opened and closed by the control unit 128 to obtain the desired resistance value.

[0104] After the controller 90 identifies the device protocol of the attached field device, the maximum power output of channel 56 that transmits power to the field device can be increased up to the maximum power set by the protocol. The controller 90 adjusts the selectable current limiting device 118 to increase the maximum power output of channel 56 from the minimum safe power output to the protocol power output as described.

[0105] If the attached field device is an APL field device, the controller 90 can also be configured to enable the user to selectively set the APL power class of port 62 that transmits power to the field device. The APL standard defines a plurality of power classes that can be applied to each port of an APL field switch.

[0106] The use of a selectable current limiting device for selectively setting the power class of an APL field switch is disclosed in the applicant's co-pending PCT patent application, filed on the same day as this application under Attorney Docket No. 14-1381-PCT, entitled "APL Field Switch with Dynamic Power Allocation," with the United States Patent and Trademark Office as the receiving office, and this co-pending application is incorporated by reference as if fully set forth herein.

[0107] The protocol detection circuit 88 further includes an ammeter 134 disposed in each channel 56 (see FIG. 3), and each ammeter is connected as an input to the controller 90. For example, a commercially available integrated circuit Hall effect current sensor can be adapted for use in accordance with this disclosure.

[0108] When a data-only field device is attached to the channel 56, the channel 56 need not supply power to the field device during protocol detection or during normal operation of the field device. Each channel 56 includes a power relay 136 disposed on a channel power line 68 that is connected to and controlled by the controller 90. The channel data line 66 is between the channel power relay 136 and the channel port 62. Data can be transmitted via the channel data line regardless of whether the power relay 136 is open or closed.

[0109] When a field device is first attached to the channel port 62, the channel power relay 136 is closed and the channel 56 can supply minimum safe power to the field device. The controller 90 reads the channel ammeter 134 to detect whether the field device is drawing power through the channel 56. This helps the controller determine whether the field device is a data-only field device (no current, so no power is drawn) or a power and data field device (current is drawn, so power is drawn).

[0110] When the controller 90 detects that the field device is a data-only field device, the controller opens the channel power relay 136 so that power is not transmitted to the field device via channel 56. Since the controller 90 has determined that the field device is a non-APL field device (the APL protocol is a protocol for power and data), the field device only needs to be connected to the data-only protocol detection circuit 102 associated with the data-only protocol for protocol detection.

[0111] When the controller 90 detects that the field device draws power and that the field device is a data-and-power field device, the channel power relay 136 remains closed so that power is transmitted to the field device during protocol detection and during normal operation of the field device. The controller first attempts to detect the APL protocol, and if that fails, it connects the field device only to the protocol detection circuit 102 associated with the data-and-power protocol for protocol detection.

[0112] The controller 90 is not only active for protocol detection, but also active when setting the ability of channel 56 to transmit power, and is also active when setting the maximum power output of the channel if the channel is transmitting power. FIG. 14 summarizes the connection of the controller 90 to the components associated with each channel 56 and each protocol detection circuit 102 for protocol detection and power control.

[0113] The controller 90 maintains in memory data related to the installed protocol detection circuit (e.g., whether it is a protocol detection circuit for data only or for power and data), the protocol circuit, and the relays associated with the channels, etc., and may include the current draw, the power state of the current limiting device, and the protocol of the attached field device. The controller periodically reads the ammeter to maintain the state information in memory for each channel.

[0114] When the controller determines that a field device is attached to the channel port, the controller starts protocol detection to determine the protocol of the attached field device. The stepwise current draw in any given channel caused by connecting the field device to the channel (e.g., an increase in current flow from zero flow) can be detected by the controller monitoring the channel ammeter. The stepwise change in the current draw can be used as an interrupt or event to cause the controller 90 to start protocol detection of the field device attached to the channel.

[0115] Figures 15 and 16 include flowcharts illustrating steps that the controller may take when determining the protocol of a field device attached to channel port 62. The channel 56 of the port is in an initial state where the channel power relay 136 is closed, the channel data relay 116 is open, and the channel protocol adapter detection relay 114 is open. The channel current limiting device 118 is in its minimum safe power output state, and the channel pass-through connector 82 is attached.

[0116] After detecting that the field device is connected to channel port 62, the controller reads the channel ammeter 134.

[0117] Without current draw, the controller 90 determines that the field device is a data-only field device. The controller opens the channel power relay 136 to disconnect the field device from the power supply during protocol detection and closes the channel's conventional protocol detection relay 114 to enable the channel to access the data-only protocol detection circuit (if it exists). The controller checks whether a data-only protocol detection circuit exists. If it does, the controller sequentially closes each data-only protocol detection circuit relay 110, issues commands to the field device until a response is received from the field device, thereby identifying the protocol of the field device. The controller may store the detected protocol of the channel in memory. Then, the controller displays the name of the detected protocol. If there is no data-only protocol detection circuit or no response is received, the controller displays that the protocol was not detected. The controller opens the channel's conventional protocol detection relay 114 to end the protocol detection process.

[0118] With current draw, the field device is a power and data field device. Then, the controller closes the channel data relay 116 and issues commands to the field device to check whether the field device is an APL field device. When the field device responds, the controller sets the state of the channel current limiting device 118 to the state corresponding to the default APL port power class and displays that the APL protocol has been detected.

[0119] If the attached field device is an APL field device, the connection process of the field device is complete. The APL field device communicates via the channel port 62 and receives power.

[0120] If no response is received, the APL field device is a conventional power and data field device. The controller attempts to detect the field device protocol using only the power and data protocol detection circuits, as described above for the data-only protocol. If the protocol is detected, the controller 90 sets the state of the channel current limiting device to the power state compliant with the protocol and displays the name of the detected protocol. If the protocol is not detected, the controller displays that the protocol was not detected. The controller opens the conventional protocol detection relay 114 of the channel to end the protocol detection process.

[0121] Communication between the controller and the field device during protocol detection can be done at a low speed. The controller 90, the channel 56, and the protocol detection circuit 102 require only the minimum hardware necessary to maintain low-speed communication during protocol detection.

[0122] When it is detected that the attached field device is a conventional non-APL field device, the field device connection process is not yet complete. The user must insert a compatible protocol adapter into the protocol adapter connector of the channel to enable data communication between the network trunk 28 and the field device. The protocol adapter includes more expensive conventional hardware required for high-speed data communication with conventional field devices.

[0123] The user removes the channel cover 88 and the channel pass-through 82 and inserts the protocol adapter into the protocol adapter connector 72. Next, the protocol adapter is connected in series with the channel power line 68. The protocol adapter has a data line that converts between data in the APL Ethernet format and data in the field device format for high-speed bidirectional data communication between the field device and the network trunk.

[0124] Figure 17 illustrates a protocol adapter 138 that is compatible with Profibus·PA·field devices for power and data or Foundation·Fieldbus·field devices for power and data. When the adapter is installed in the protocol adapter connector 72, the protocol adapter 138 connects to the connector terminals 78, 80 and includes a power line 140 having end terminals 142, 144 that arrange the power line 140 in series with the channel power line 68. The power transmitted through the protocol adapter is also used to power the protocol adapter.

[0125] A data line 146 having both ends connected to the adapter power line 140 extends parallel to the adapter power line, extracts data from the adapter power line, and injects data into it.

[0126] The adapter data line 146 includes a conventional data line segment 148 and an APL data line segment 150 that extend from both ends of the channel power line 140. The conventional data line segment 148 extends from the channel port side of the adapter power segment. The conventional data line segment is connected to a conventional transceiver 152 that can transmit and receive data in the Profibus / FF format. Next, the conventional transceiver 152 is connected to a Fieldbus or Profibus·DP·ASIC (Application-Specific Integrated Circuit) 154 that enables high-speed data transmission through the conventional transceiver 152.

[0127] The APL data line segment 150 is connected to an APL transceiver 156 that enables high-speed data transmission of data in the APL Ethernet format. A CPU that functions as a protocol converter 158 for converting the data stream passing through the data line 146 between the APL Ethernet data format and the Profibus / FF data format is arranged between the APL transceiver 156 and the Profibus / FF·ASIC 154.

[0128] The adapter data line 148 functions to convert data in the APL Ethernet format transmitted to the field device into compatible Profibus / FF data transmitted to the field device, and to convert data in the Profibus / FF format transmitted from the field device to the APL field switch data terminal into data in the APL Ethernet format transmitted to the APL field switch data terminal.

[0129] The protocol adapter 138 may also include a communication line segment 160 that connects independently to the controller 90 for communication between the controller and the adapter CPU 158 when the protocol adapter is inserted into the protocol adapter connector 72. When powered on, the protocol adapter 138 can communicate its presence and its protocol to the controller 90. The controller can verify that the protocol of the adapter is the same as the detected protocol, and if not, open the channel power relay and warn the user of the protocol mismatch.

[0130] FIG. 18 illustrates a protocol adapter 162 that is similar to the protocol adapter 138 but is compatible with Modbus·RTU·field devices that only handle data. The adapter power line 164 is configured to draw power from the channel power line 68 to power only the protocol adapter instead of transmitting power via a power adapter.

[0131] The illustrated protocol adapter 162 includes a communication line segment 166. When the protocol adapter 162 is installed in the protocol adapter connector 72, the controller 90 detects the connection to the communication line segment 160 and opens the channel power line 68 to power the installed protocol adapter 162. Then, the protocol adapter 162 can communicate its presence to the controller for protocol verification as described for the power and data protocol adapter 138.

[0132] FIG. 19 illustrates an APL field switch 30 having several installed protocol adapters 138 (spur lines and field devices are not shown).

[0133] FIG. 20 illustrates an APL field switch 168 of a second embodiment. The APL field switch 168 is similar to the APL field switch 30, but does not include a protocol detection circuit for detecting the protocol of a field device when the field device is first connected to a channel port. The ammeter can be eliminated. When attaching a non-APL field device to a port channel, the user must insert a compatible protocol adapter, such as protocol adapter 138 or protocol adapter 162, into the channel's protocol adapter connector 72 to complete the connection of the field device to the APL field switch. The protocol adapter can include a communication line segment for communicating its presence and protocol to the controller, as described above, to enable the controller 90 to set the appropriate power state of the channel current limiting device based on the protocol.

[0134] When attaching an APL field device to a port channel with a power adapter pass-through 82 installed, the APL field device 168 can detect the connection of the field device, determine that no protocol adapter is installed, confirm the installation of the APL field device, and set the power state of the channel current limiting device to the power state associated with the default power class of the port.

[0135] When using the APL field switch 168, the user may want to utilize protocol detection to identify or verify the protocol of the field device before attaching the field device to the APL field switch. FIG. 21 illustrates a battery-powered handheld protocol detection tool 170 that includes the protocol detection circuit shown in FIG. 22. The detection tool includes a protocol detection circuit 102 that can be selectively connected, similar to the protocol detection circuit 102 in the APL field switch 32. The protocol detection circuit 102 is connected to an APL channel 56 similar to the channel 56 in the APL field switch 32, but extends continuously to the two-wire port 62 without a protocol adapter connector. The tool has a controller 90 that determines the field device as described above for the APL field switch 30.

[0136] The user connects the field device D to the port 62 using the two-wire spur S. The controller 90 of the tool goes through its protocol detection routine as shown in FIGS. 12 and 13. The protocol detection result can be displayed on the tool's display and / or reported via a wired or wireless connection to a smartphone, tablet, computer, etc.

[0137] The relay according to the present disclosure may be an analog relay, a transistor relay, a mechanical relay, or the like. The data line, which is a conductor, can transmit data including commands and responses as electrical signals compliant with the field device protocol to which the data line receives the data.

[0138] The present disclosure includes one or more exemplary embodiments described in detail, but each of the one or more embodiments is modifiable, and the scope of the present disclosure is not limited to the exact details described herein, and includes changes such as material selection, size, number of protocol detection circuits, field device protocols associated with the protocol detection circuits, etc., and such improvements that would be apparent to those skilled in the art, including such changes and modifications (but not limited to these) included in the appended claims.

Claims

1. A method for automatic protocol detection of a field device for a process control network in response to the field device, the field device being attached to a port of a field switch of the process control network, the field switch comprising a plurality of ports and a plurality of channels, each port being connected to a respective channel, each port being configured to connect a field device to the channel connected to the port, each channel being configured to transmit data to and from the port connected to the channel, the field switch comprising a set of two or more protocol detection circuits, each protocol detection circuit of the set of two or more protocol detection circuits being compatible with a respective field device protocol different from the remaining field device protocols of the set of two or more protocol detection circuits, and being capable of transmitting data to and receiving data from the port connected to the channel when connected to the channel, the set of two or more protocol detection circuits not being directly connected to any of the plurality of channels at the start of the method, the method comprising: (a) In response to attaching a field device to one of the plurality of ports of the field switch, connecting a first protocol detection circuit of the set of two or more protocol detection circuits to the channel connected to the port while maintaining the other protocol detection circuits disconnected from the channel; (b) Attempting to communicate with the attached field device via the protocol detection circuit connected to the channel using the protocol of the protocol detection circuit connected to the channel; (c) If, in step (b), it is determined that the attached field device is compatible with the protocol of the connected protocol detection circuit, identifying the field device as having the protocol associated with the connected protocol detection circuit, and then (d) Disconnecting the connected protocol detection circuit from the channel, and (e) Ending the method and performing steps (f) In step (b), if it is determined that the field device is not compatible with the protocol of the connected protocol detection circuit, (g) Disconnecting the connected protocol detection circuit from the channel; (h) Determining whether there is a protocol detection circuit that is not yet connected to the channel in the set of two or more protocol detection circuits, and (i) In step (h), if it is determined that there is no protocol detection circuit that is not yet connected to the channel, (j) Identifying the field device as having an unconfirmed protocol, and (k) Ending the method Executing the steps Proceeding to the steps (l) In step (h), if it is determined that there is one or more protocol detection circuits that are not yet connected to the channel, then, instead of the first protocol detection circuit, the next protocol detection circuit in the set of two or more protocol detection circuits that are not yet connected to the channel connected to the field device is used to repeat the method starting from step (a); including At the end of the method, all protocol detection circuits in the set of two or more protocol detection circuits are disconnected from the plurality of channels.

2. Step (b) includes (m) Sending a command to the field device via the first protocol detection circuit, and (n) Determining whether the field device responded to the command or did not respond to the command The method according to claim 1, including.

3. Each of the two or more protocol detection circuits can be selectively connected to and disconnected from each channel of the plurality of channels. Each protocol detection circuit includes a first relay that is normally open. Step (a) includes (m) Closing the first relay of the first protocol detection circuit as part of connecting the first protocol detection circuit to the channel connected to the field device including Step (d) includes (n) Opening the first relay closed in step (m) as part of disconnecting the protocol detection circuit attached to the channel from the channel The method according to claim 1, including.

4. Each channel of the plurality of channels is configured to transmit data via the channel that is compatible with a channel protocol not associated with any of the protocol detection circuits of the set of two or more protocol detection circuits. Each channel of the plurality of channels includes a data line configured to transmit data via the channel using the channel protocol. The data line of each channel of the plurality of channels includes a respective second relay on the data line. Step (a) is (o) While maintaining the second relay on the data line of the channel in a closed state and maintaining all of the first relays in the set of two or more protocol detection circuits in an open state to determine whether the field device is compatible with the channel protocol, transmitting data using the channel protocol via the data line of the channel; (p) If, in step (o), it is determined that the field device is compatible with the channel protocol, identifying the field device as having the channel protocol and attaching a protocol adapter configured to convert between the identified protocol and the channel protocol, the protocol adapter being compatible with the identified protocol, to a protocol adapter connector disposed on the channel, and completing step (a) to end the method while maintaining the second relay on the data line of the channel in the closed state; (q) If, in step (o), it is determined that the field device is not compatible with the channel protocol, opening the second relay on the data line of the channel connected to the field device and maintaining the second relay in an open state throughout the remainder of the method. The method of claim 3, comprising: Claim 5 Each protocol detection circuit of the set of two or more protocol detection circuits is connected in parallel with each channel of the plurality of channels by a respective channel data line extending from the protocol detection circuit to the channel, and each channel data line includes a respective third relay that is normally open on the channel data line. Step (a) further comprises (o) As part of connecting the first protocol detection circuit to the channel, closing the normally open third relay in the channel data line extending from a common data line to the channel connected to the port. including Steps (e) and (k) each (p) As part of the end of the method, opening the relay closed in step (o), thereby disconnecting the channel from all of the protocol detection circuits in the set of two or more protocol detection circuits; and (q) While repeating the method with the next protocol detection circuit, maintaining the closed third relay in a closed state. The method according to claim 3, comprising. **Claim 6** Each channel of the plurality of channels is configured to transmit data compatible with a channel protocol that is not associated with any protocol of the set of two or more protocol detection circuits, and step (a) is (m) Before connecting the first protocol detection circuit to the channel, when starting the method, determining whether the field device is compatible with the channel protocol; and (n) In step (m), when it is determined that the field device is compatible with the channel protocol, identifying the field device as having the channel protocol and completing step (a) to end the method; and (o) In step (n), when it is determined that the field device is not compatible with the channel protocol, continuing the remainder of step (a) by connecting the first protocol detection circuit to the channel. The method according to claim 1, comprising. **Claim 7** The channel protocol of each channel of the plurality of channels is compatible with the Ethernet Advanced Physical Layer (APL) specification. The method according to claim 6. **Claim 8** Each channel of the plurality of channels includes a respective protocol adapter connector, and the protocol adapter connector can receive a protocol adapter that converts data transmitted through the protocol adapter connector between the channel protocol and a field device protocol different from the channel protocol when attached to the protocol adapter connector. Step (e) is (p) attaching a protocol adapter compatible with the identified field device protocol to the protocol adapter connector of the channel connected to the port before ending the method The method according to claim 6, comprising: **Claim 9** The protocol adapter connector of each channel of the plurality of channels normally opens the channel, the field switch comprises a plurality of slots, and each slot is open for receiving a protocol adapter in the slot for each protocol adapter connector of the plurality of channels, Step (a) is (q) attaching a cover to the field switch that closes the slot open for the protocol adapter connector of the channel connected to the port before performing step (m), the cover providing continuity of the channel across the protocol adapter connector when attached to the field switch; (r) attaching a pass-through connector to the protocol adapter connector of the channel connected to the field device, the attached pass-through connector providing continuity of the channel across the protocol adapter connector; comprising Step (p) includes removing the pass-through connector attached to the protocol adapter connector in step (q) from the protocol adapter connector before attaching the protocol adapter to the protocol adapter connector. Step (p) further includes removing the cover from the field device to open the slot before attaching the protocol adapter to the protocol adapter connector. The method according to claim 8. **Claim 10** The field switch can transmit power to the field device connected to the channel among the plurality of channels via the plurality of channels. Before performing step (a), the method (m) detecting the start of power transmission via one of the plurality of channels to detect that the field device is connected to the channel; (n)responding to detecting the connection of the field device to the channel, starting step (a); The method according to claim 1, comprising:

11. The field switch includes a controller connected to each channel of the plurality of channels and each protocol detection circuit of the set of two or more protocol detection circuits, and the controller is configured to execute stored instructions to execute the method of detecting the protocol of the field device; Step (c) includes generating, by the controller, an output signal used to identify the identified protocol of the field device to a user of the field switch. The method according to any one of claims 1 to 10.

12. Step (a) further includes: (a)(1) Responding to attaching the field device to the port, before connecting the first protocol detection circuit to the channel, determining whether the field device is drawing power via the power line of the channel, whereby the connected field device can receive power via the power line when connected to the channel; (a)(2) In step (a)(1), when it is determined that the field device is drawing power; (a)(2)(a) Connecting only the protocol detection circuit associated with the data and power protocols among the set of two or more protocol detection circuits to the channel when executing the method; and (a)(2)(b) Limiting the power transmitted via the power line of the channel to a minimum safe power to protect the attached field device while attempting to determine the protocol of the field device, and when the field device protocol is identified; (a)(2)(b)(1) Before ending the method, increasing the power transmitted to the field device to at most the maximum power permitted by the identified field device protocol; Executing one of the steps; and (a)(3) In step (a)(1), when it is determined that the field device is not drawing power via the power line of the channel; (a)(3)(a) When performing the method, connecting only the protocol detection circuits associated with the data-only protocols among the set of two or more protocol detection circuits to the channel, and (a)(3)(b) Opening the power line of the channel to prevent power from being transmitted to the field device via the channel while the field device is attached to the port (wherein) performing one of the steps (wherein) the method according to claim 1. (Claim 13) (wherein) a field switch for connecting a plurality of field devices to a process control network, the process control network being connected to the field switch, the field device being capable of identifying the protocol of the field device connected to the field switch, the field switch (wherein) one or more terminals for connecting the field switch to the process control network, the field switch being configured to receive power at the field switch, receive data at the field switch, and transmit data from the field switch to the process control network; (wherein) a plurality of channels for transmitting data and power between the terminal and the field device, the field device being connected to the channel, each channel comprising a respective port configured to connect the field device to the channel, the channel being configurable to transmit data to and from the field device attached to the port; A set of two or more protocol detection circuits that is the only protocol detection circuit of the field device, wherein each protocol detection circuit of the set of two or more protocol detection circuits is compatible with a respective field device protocol different from the remaining field device protocols of the set of two or more protocol detection circuits, each protocol detection circuit of the set of two or more protocol detection circuits is selectively connectable to each of the plurality of channels, and when the protocol detection circuit is connected to the channel, it can transmit data to and receive data from the port connected to the channel using the protocol associated with the protocol detection circuit, a set of two or more protocol detection circuits. A controller comprising a microprocessor configured to execute instructions stored in non-volatile memory to perform protocol detection, the controller being connected to each protocol detection circuit of the set of two or more protocol detection circuits, the controller being able to selectively connect and disconnect each protocol detection circuit of the set of two or more protocol detection circuits to and from each of the plurality of channels, the controller, when a field device is connected to the channel, sequentially connecting the protocol detection circuits of the set of two or more protocol detection circuits to one of the plurality of channels and being able to determine whether the protocol of the field device can be identified using the protocol detection circuits of the set of two or more protocol detection circuits, the controller being able to disconnect all of the protocol detection circuits of the set of two or more protocol detection circuits from the channel after determining whether the protocol of the field device connected to the channel can be identified using the set of two or more protocol detection circuits, thereby enabling the set of two or more protocol detection circuits to be used in identifying the protocol of the next field device connected to the field switch, a controller. A field switch comprising the same.

14. The field switch is configured to connect to a process control network using a network protocol, and each channel of the plurality of channels includes a respective protocol adapter connector disposed in series with the port of the channel in the channel. The protocol adapter connector is configured to convert between a protocol different from the network protocol to enable a field device connected to the channel to communicate via the process control network using the different protocol. The channel is configured to removably receive a protocol adapter, whereby a field device having a protocol incompatible with the protocol of the process control network can be used in the process control network when connected to the field switch. The field switch according to claim 13.

15. The protocol adapter connector of each channel of the plurality of channels normally opens the channel, and the protocol adapter connector is configured to removably attach a pass-through connector to the channel. The pass-through connector provides electrical continuity of power and data across the protocol adapter connector, thereby closing the channel and enabling transfer of power and data across the protocol adapter connector when attached to the protocol adapter connector. The field switch includes a plurality of slots, each slot being open to a respective protocol adapter connector of the plurality of channels for receiving a protocol adapter in the slot. The pass-through connector is configured as a cover that can be attached to the field switch to close the slot of the field switch. The cover provides electrical continuity across the protocol adapter connector in the slot when closing the slot. The field switch according to claim 14.

16. The controller according to claim 14, wherein when the protocol of the field device connected to the field switch is identified, the controller is configured to generate and transmit data used to notify the user of the protocol of the field device.

17. Each individual protocol detection circuit of the set of two or more protocol detection circuits includes a first relay that is normally open and disposed in the individual protocol detection circuit, and the first relays of the set of two or more protocol detection circuits are operably connected to the controller, and when attempting to identify the protocol of the connected field device, the controller is enabled to selectively open and close the first relay. The field switch according to claim 13.

18. The field switch is configured to connect to a process control network using a network protocol different from any of the protocols of the set of two or more protocol detection circuits. Each of the plurality of channels is connected to the controller. Each of the plurality of channels includes a second relay for each channel, the second relays of the plurality of channels are operably connected to the controller, and the controller can selectively open and close the second relay when attempting to identify the protocol of the field device connected to the controller. When attempting to identify the protocol of a field device attached to one of the plurality of channels, the controller is configured to first close the second relay of the channel and open the first relay to determine whether the field device is compatible with the network protocol. When attempting to identify the protocol of a field device attached to one of the plurality of channels, the controller is configured to maintain the second relay of the channel in an open state if the attached field device is not compatible with the network protocol. When the controller attempts to identify the protocol of a field device attached to one of the plurality of channels, after determining that the field device is compatible with the network protocol, while the field device is attached to the channel, the second relay of the channel is configured to be maintained in a closed state. The field switch according to claim 17.

19. Each protocol detection circuit of the set of two or more protocol detection circuits is connected to each channel of the plurality of channels by a channel data line extending from the channel. Each of the respective channel data lines includes a respective third relay disposed on the channel data line, and the third relay of the channel data line is operably connected to the controller. When the controller attempts to identify the protocol of a connected field device, the controller can selectively open and close the third relay. The controller is configured to maintain the third relay of the channel data line extending from the channel in a closed state and maintain other third relays in an open state while attempting to identify the protocol of a field device attached to one of the plurality of channels. The set of two or more protocol detection circuits is connected to a common data line, and each of the channel data lines extending from the plurality of channels is connected to the common data line. The field switch according to claim 18.

20. Each channel of the plurality of channels can transmit power to a field device connected to the channel via the channel. Each channel of the plurality of channels includes a power limiting device capable of selectively limiting the power transmitted from the channel to a field device attached to the channel. The power limiting device is operably connected to the controller, and the controller can selectively limit the power transmitted to a field device attached to the channel. The controller is configured to detect that power is being sent to a field device attached to one of the plurality of channels, and while the controller attempts to determine the protocol of the field device, limit the power being sent to the field device via the channel to a minimum safe power. After determining the protocol of the field device, the controller is configured to increase the power sent to the field device via the channel, whereby the power sent to the field device is at most the maximum power permitted by the protocol of the field device. The field switch according to claim 13. **Claim 21** When the controller identifies the protocol of a field device connected to the field switch, it is configured to generate and transmit data used to notify the user of the protocol of the field device. When the controller fails to identify the protocol of a field device connected to the field switch, it is configured to generate and transmit data used to notify the user of the field switch of the failure. The controller is configured to detect the start of power transmission to a field device attached to any one of the plurality of channels, and in response, start an attempt to identify the protocol of the attached field device. The field switch according to claim 13. **Claim 22** Each channel of the plurality of channels includes a power line for transmitting power to a field device of power and data attached to the channel via the channel. Each channel of the plurality of channels includes a relay in the power line of the channel, and the relays of the plurality of channels are operably connected to the controller, enabling the controller to selectively open and close each of the relays. When the controller determines that a data-only field device is attached to one of the plurality of channels, the controller is configured to keep the relay of that channel in an open state. The field switch according to claim 13.

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