System and method for safety signaling using optical fiber

Abstract

The safety signaling system comprises a panel including an HMI for setting the safety condition of a first operator to one of VOTE and NO VOTE, a first optical transceiver for connecting to a first optical fiber, and a second optical transceiver for connecting to a second optical fiber. A panel control circuit connected between the HMI and the first transceiver activates the first transceiver to transmit a continuous wave (CW) optical signal to the first optical fiber only while the HMI has set the safety condition of the first operator to VOTE. The remote interface comprises a third optical transceiver for connecting to the first optical fiber, a fourth optical transceiver for connecting to the second optical fiber, and a remote interface control circuit connected to the third transceiver. The interface control circuit sets the first received safety condition to VOTE only while the CW optical signal is being received by the third transceiver and uses the first received safety condition to determine the current first remote safety condition.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims priority to U.S. Provisional Patent Application Ser. No. 63 / 497,085, filed Apr. 19, 2023, which is incorporated herein by reference.

[0002] The following disclosure relates to a safety protocol over optical fiber that can provide critical arms and abort signals with no latency and full determinism (i.e., no firmware or software within the loop) up to 20 km or more. This is highly important for any remote weapon system. In one embodiment, the safety signaling system is suitable for signaling a high - energy laser weapon system (HELWS).

Background Art

[0004] In one embodiment, the safety signaling system includes a first voltage-optical converter (VTLC) located on the operator panel, configured to output a first optical signal of a first predetermined optical frequency only when it receives a predetermined first voltage indicating a first operator safety condition set to a first value. A first optical fiber is operably connected at its first end to the first VTLC to receive the first optical signal output by the first VTLC and to propagate the first optical signal to a second end. A first optical voltage converter (LTVC) is located on the remote interface and operably connected to the second end of the first optical fiber to receive the first optical signal and is configured to output a predetermined second voltage only when it receives the first optical signal. A remote interface control circuit is located on the remote interface and operably connected to the first LTVC to receive a predetermined second voltage when it is output by the first LTVC and is configured to set a first receiving safety condition to a first value when it receives the predetermined second voltage. The first optical signal provides a first forward channel. In the remote interface control circuit, a first receive safety condition set to a first value determines that the first operator safety condition is currently set to a first value. The remote interface control circuit uses the first receive safety condition to determine the current value of the first remote safety condition.

[0005] In one embodiment, the current value of the first remote safety condition is transmitted to the remote system by the remote interface control circuit.

[0006] In another embodiment, the first optical signal is a continuous wave (CW) signal.

[0007] In yet another embodiment, no software, computer, or coding is used to transmit a first voltage, a first optical signal, and a second voltage between the safety operator panel and the remote interface.

[0008] In another embodiment, the remote interface control circuit sets the current value of the first remote safety condition to the current value of the first received safety condition.

[0009] In a further embodiment, the remote interface control circuit further comprises a fault latch subcircuit operably mounted on the first LTVC to monitor a second voltage. The fault latch subcircuit is configured to output a fault value to the remote interface control circuit when it detects a predetermined interruption of the second voltage. The remote interface control circuit is further configured to set the current value of the first remote safety condition to the second value when it receives a fault value from the fault latch subcircuit, regardless of the current value of the first remote safety condition. The remote interface control circuit is further configured to hold the current value of the first remote safety condition at the second value until the fault latch subcircuit is reset.

[0010] In yet another embodiment, the safety signaling system further comprises a second VTLC located at the remote interface, the second VTLC configured to output a second optical signal at a predetermined second optical frequency, the second optical frequency being different from the first optical frequency, the second optical signal transmits the quality of service (QoS) attribute of the first forward channel. The first optical fiber is operably connected at its second end to the second VTLC to receive the second optical signal output by the second VTLC and to propagate the second optical signal to the first end. A second LTVC is located on the safety operator panel and operably connected to the first end of the first optical fiber to receive the second optical signal and is configured to output a QoS voltage indicating the QoS attribute of the first forward channel. The second optical signal provides the first backhaul channel.

[0011] In further embodiments, the first VTLC and the second LTVC are provided by a first bidirectional modular transceiver located on the operator panel. The second VTLC and the first LTVC are provided by a second bidirectional modular transceiver located on the remote interface.

[0012] In another embodiment, the SSOF system further comprises a third VTLC located on the operator panel, configured to output a third optical signal of a predetermined third optical frequency indicating a network message. A second optical fiber is operably connected at its first end to the third VTLC to receive the third optical signal output by the third VTLC and to propagate the third optical signal to its second end. A third LTVC is located on the remote interface, and the third LTVC is operably connected to the second end of the second optical fiber to receive the third optical signal, and the third LTVC is configured to output a third voltage indicating a network message when it receives the third first optical signal. A fourth VTLC is located on the remote interface, and the fourth VTLC is configured to output a fourth optical signal of a predetermined fourth optical frequency, the fourth optical frequency being different from the third optical frequency, and the fourth optical signal transmitting a different network message. The second optical fiber is operably connected at its end to the fourth VTLC to receive the fourth optical signal output by the fourth VTLC and to propagate the fourth optical signal to the first end. The fourth LTVC is located in the safety operator panel and is operably connected to the first end of the second optical fiber to receive the fourth optical signal. The fourth LTVC is configured to output another network voltage indicating another network message. Together, the third and fourth optical signals provide a bidirectional pair of network communication channels.

[0013] In yet another embodiment, the third VTLC and third LTVC are provided by a third bidirectional modular transceiver located on the operator panel, and the fourth VTLC and fourth LTVC are provided by a fourth bidirectional modular transceiver located on the remote interface.

[0014] In another embodiment, the safety signaling system comprises a human-machine interface (HMI) for setting the value of a first operator safety condition to one of status=VOTE and status=NO VOTE, a first bidirectional optical transceiver configured to connect to a first optical fiber, a second bidirectional optical transceiver configured to connect to a second optical fiber, and an operator panel control circuit operably connected between the HMI and the first bidirectional optical transceiver. The panel control circuit activates the first bidirectional optical transceiver to transmit a continuous wave (CW) optical signal to the connected first optical fiber only while the HMI is setting the value of the first operator safety condition to status=VOTE. The remote interface includes a third bidirectional optical transceiver configured to connect to a first optical fiber, a fourth bidirectional optical transceiver configured to connect to a second optical fiber, and a remote interface control circuit operably connected to the third bidirectional optical transceiver. The interface control circuit sets the value of the first receive safety condition to status=VOTE only while the CW optical signal is being received by the third bidirectional optical transceiver. The remote interface control circuit uses the value of the first receive safety condition to determine the current value of the first remote safety condition.

[0015] In one embodiment, the system includes a first network interface circuit located on the operator panel and operably connected to a third bidirectional optical transceiver. A second network interface circuit is located on the remote interface and operably connected to a fourth bidirectional optical transceiver. The third and fourth bidirectional transceivers are configured to transmit network messages to each other via a connected second optical fiber and to relay network messages to and from an external source.

[0016] In another embodiment, the remote interface control circuit further comprises a latch subcircuit operably mounted on a second bidirectional optical transceiver to monitor the received CW optical signal. The latch subcircuit is configured to output a fault value to the remote interface control circuit when it detects an interruption in the received CW optical signal. The remote interface control circuit is further configured to set the current value of the first remote safety condition to status=NO VOTE when it receives a fault value from the latch subcircuit, regardless of the current value of the first remote safety condition. The remote interface control circuit is further configured to maintain the current value of the first remote safety condition at status=NO VOTE until the latch subcircuit is reset.

[0017] For a more complete understanding, please refer to the following explanation in conjunction with the attached diagrams. [Brief explanation of the drawing]

[0018] [Figure 1] A block diagram of a single-channel safety signaling system according to one embodiment is shown. [Figure 2] A block diagram of a 3-channel safety signaling system in another embodiment is shown. [Figure 3] A front right perspective view of the operator control panel of a 3-channel safety signaling system in a further embodiment is shown. [Figure 4] Figure 3 shows a front left perspective view of the operator control panel. [Figure 5] This shows an exploded view of the front right of the operator control panel. [Figure 6] This shows an exploded view of the front left of the operator control panel. [Modes for carrying out the invention]

[0019] Referring to Figure 1, a block diagram of a single-channel system for optical fiber-based safety signaling ("SSOF system") 100 is shown. The SSOF system 100 comprises a safety operator panel 102 and a remote system interface 104 connected by one or more optical fibers 106. The remote system interface 104 may be located on or locally to any remote system 108 to be signaled by the SSOF system 100. The safety operator panel 102 may be located far from the remote system 108 at a location where it is desired to initiate safety signaling to the remote system. Preferably, the SSOF system 100 is used solely for sending safety signaling to the remote system 108, i.e., the remote system will typically have its own control system separate from the SSOF system.

[0020] The safety operator panel 102 of the SSOF system 100 can be positioned at any optically accessible distance from the remote system interface 104. As used herein, “optically accessible” means a distance at which the optical fiber 106 does not exhibit material signal loss between the safety operator panel 102 and the remote interface 104. As used herein, signal loss is considered “material” for the SSOF system 100 if it alters the reliability of the remote interface 104 in correctly receiving intended signals transmitted from the operator safety panel 102. Often, the safety operator panel 102 can be positioned at a distance from the remote system interface 104 that is both optically accessible and electrically remote. As used herein, “electrically remote” means a distance at which an electrical connection, such as a copper wire, exhibits material signal loss from length-related resistance, mutual interference, RFI, or EFI, if such a connection exists between the safety operator panel 102 and the remote interface 104.

[0021] In a preferred embodiment, each optical fiber 106 is end-to-end of a single continuous fiber without inline optical amplifiers or repeaters between the safety operator panel 102 and the remote interface 104. The use of inline optical amplifiers or repeaters on the optical fiber 106 is avoided where possible, as such devices would introduce signal delay, impose power requirements, and reduce the inherent reliability of the SSOF system 100. In some embodiments, each fiber 106 is a single continuous fiber with an end-to-end length of at least 10 km, without inline optical amplifiers or repeaters between the ends of the fiber. In other embodiments, each fiber 106 is a single continuous fiber with an end-to-end length of at least 20 km, without inline optical amplifiers or repeaters between the ends of the fiber. In yet another embodiment, each fiber 106 is a single continuous fiber with an end-to-end length of at least 30 km, without inline optical amplifiers or repeaters between the ends of the fiber.

[0022] The remote interface 104 can be attached directly to the remote system 108 or within the electrically local distance of the remote system. As used herein, the term "electrically local" means a distance where the electrical connection between the remote interface 104 and the remote system 108 shows no material signal loss from length-related electrical resistance, mutual interference, RFI, and EFI.

[0023] The SSOF system 100 includes one or more forward channels 109, each forward channel comprising a first voltage-to-optical converter (VTLC) 110 located on the safety operator panel 102, a first optical voltage converter (LTVC) 112 located on the remote interface 104, and an optical fiber 106 (indicated as "fiber 1" in Figure 1) operably connected between them. Each first VTLC 110 is operably connected to an operator control circuit 114 on the operator safety panel 102, and the operator safety panel 102 is operably connected to an operator human-machine interface (HMI) 116 on the operator safety panel. The HMI 116 may include, but is not limited to, switches 117a and buttons 117b that can be operated by the user on the operator safety panel 102 to indicate safety considerations, and indicator lights 117c that can be observed by the user to indicate the status of each channel or the entire SSOF system 100. In a preferred embodiment, no software, computer, or coding is used to transmit signals between the operator HMI 116 and the operator control circuit 114. Each first LTVC 112 is operably connected to a remote interface circuit 118 at a remote interface 104, which may be connected to a remote HMI (not shown) and / or directly to a remote system 108. In a preferred embodiment, no software, computer, or coding is used to transmit signals between the remote interface circuit 118 and the remote HMI (if present) and / or the remote system 108.

[0024] For each respective forward channel 109, each respective first VTLC 110 is configured to output each respective first optical signal 120 when receiving each respective predetermined first voltage 122 from the operator control circuit 114 and not to generate the first optical signal when the predetermined first voltage is not received. In a preferred embodiment, software, a computer, and coding are not used within the operator control circuit 114 to generate the predetermined first voltage 122. For each respective forward channel 109, each respective first optical signal 120 propagates to the operator end of each respective optical fiber 106, travels through the optical fiber, and is received by each respective first LTVC 112 from the remote end of the optical fiber. In a preferred embodiment, each respective optical fiber 106 is end-to-end of a single continuous fiber without an in-line optical amplifier or repeater between the operator end and the remote end. Each respective first LTVC 112 is configured to output each respective predetermined second voltage 124 to the remote interface circuit 118 when receiving each respective first optical signal 120 from the remote end of each respective optical fiber 106 and not to generate the predetermined second voltage when not receiving the first optical signal.

[0025] The status of various safety considerations determined by the safety operator on the operator panel 102 can be referred to as one or more operator safety conditions. A safety signaling system, such as the SSOF system 100, can use one forward channel 109 to signal each such operator safety condition to the remote interface 104. Many such operator safety conditions have binary characters, and therefore each condition can have pairs of possible values ​​such as "VOTE" and "NO VOTE", "1" and "0", "GO" and "NO GO". Thus, the state in which the remote interface 104 receives a predetermined second voltage 124 on each forward channel 109 can be referred to as "VOTE" on each forward channel, and the state in which the remote interface does not receive a predetermined second voltage 124 can be referred to as "NO VOTE". Therefore, each forward channel 109 from the operator control circuit 114 to the remote interface circuit 118 is considered deterministic. This is because the VOTE status on each forward channel in the remote interface 104 can be considered merely a result of having a predetermined first voltage 122 on each forward channel in the operator panel 102. In other words, the appearance of a VOTE status for each channel in the remote interface 104 leads to the conclusion that a VOTE status currently exists for each channel in the safety operator panel 102 and that each channel is functioning properly. Any interruption of each first voltage 122, or a failure of each first VTLC 110, a break in each optical fiber 106, or a failure of each first LTVC 112 would result in a NO VOTE status on the remote interface 104 on each forward channel 109.

[0026] In some embodiments, the HMI 116 in the safety operator panel 102 may be configured to selectively move between a VOTE position and a NO VOTE position for each forward channel 109. The operator control circuit 114 may then be configured to output a predetermined respective first voltage 122 only when the HMI 116 is in the VOTE position for each forward channel 109. Thus, when the operator moves the HMI 116 to set the VOTE status for a selected forward channel 109, the SSOF system 100 immediately reflects the VOTE status for the selected forward channel at the remote interface 104 (i.e., at the speed of light through the fiber). When the operator moves the HMI 116 to the NO VOTE position for a first forward channel 109, or when there is a fault along the selected forward channel, the SSOF system 100 immediately reflects the NO VOTE status for the selected forward channel at the remote interface 104 (i.e., at the speed of light through the fiber).

[0027] In a preferred embodiment, the SSOF system 100 utilizes continuous wave (CW) light having a first predetermined frequency for the first optical signal 120. Due to its continuous nature, CW light has advantages for use in the forward channels of the SSOF system 100 compared to other signal forms (e.g., modulated or pulsed signals), for example, that interruptions in CW light for any period of time are detectable. In contrast, short-term interruptions in modulated or pulsed optical signals, such as interruptions occurring between expected peaks or pulses, may not be immediately detected (especially if the interruption is transient or intermittent). In some embodiments, the remote interface circuit 118 may further include one or more fault latch subcircuits 125 for forward channels 109, configured such that when an interruption in either the first optical signal 120 or the second voltage 124 of each forward channel is detected, the fault latch subcircuit sets the remote interface circuit to NO VOTE status for that forward channel, and the status remains NO VOTE for that forward channel even when the first optical signal or the second voltage is resumed, until the system is reset by the operator.

[0028] For example, Figure 1 shows an SSOF system 100 having a single forward channel 109a. The forward channel 109a comprises a first optical fiber 106a (indicated as "fiber 1" in Figure 1) operably connected between a first VTLC 110a and a first LTVC 112a. The first VTLC 110a is operably connected to an operator control circuit 114 in an operator safety panel 102, and the operator safety panel 102 is operably connected to an operator HMI 116 in the operator safety panel. The first LTVC 112a is operably connected to a remote interface circuit 118 in a remote interface 104, and the remote interface 104 is connected to a remote HMI (not shown) and / or directly to a remote system 108. The first VTLC 110a is configured to output a first optical signal 120a having a predetermined first optical frequency / wavelength (e.g., frequency "A") when it receives a predetermined first voltage 122a from the operator control circuit 114, and not to generate a first optical signal when the first voltage is not received. Each first optical signal 120a is propagated to the operator end of the optical fiber 106a, travels through the optical fiber, and is received by the first LTVC 112a from the remote end of the optical fiber. The state in which a predetermined second voltage 124a is received on the forward channel 109a at the remote interface 104 is called "VOTE" on the forward channel 109a, and the state in which the second voltage is not received at the remote interface is called "NO VOTE" on the forward channel. The forward channel 109a is considered deterministic from the operator control circuit 114 to the remote interface circuit 118. This is because the VOTE status on the forward channel in the remote interface 104 can simply be a result of the forward channel having a predetermined first voltage 122a on the operator panel 102, indicating that the forward channel is not damaged and is functioning properly.

[0029] Referring further to Figure 1, in some embodiments, the SSOF system 100 may further comprise one or more “communication feedback” or “backhaul” channels 126, each having a second optical signal 127 that utilizes the same optical fiber 106 as one of the forward channels, but has a second predetermined optical frequency / wavelength (e.g., frequency “B”) that is different from a first predetermined frequency / wavelength of the forward channel on that optical fiber. Such backhaul channels 126 can be used to provide direct feedback regarding the signal integrity of the associated forward channel 109 and / or the physical integrity of the optical fiber 106 used by the forward channel (collectively, “quality of service” or “QOS”). Each backhaul channel 126 may comprise each second VTLC 128 located at the remote interface 104, each second LTVC 130a located at the safety operator panel 102, and each optical fiber 106 operably connected between them. In some embodiments, the VTLC and LTVC devices required to operate each forward channel 109 and each backhaul channel 126 on a single fiber 106 can be provided by pairs of bidirectional (BiDi) modular transceivers 132, 134, such as SFP transceivers. A first BiDi modular transceiver 132 located on the operator panel 102 can provide a first VTLC 110 and a second LTVC 130, and a second BiDi modular transceiver 134 located on the remote interface 104 can provide a second VTLC 128 and a first LTVC 112. The second optical signal 127 of the backhaul channel 126 can be CW or modulated. In some embodiments, the QoS information for the backhaul channel 126 is provided by the remote interface circuit 118, but in other embodiments, such as those using modular SFP transceivers 132, 134, the QoS information can be generated by the modular transceivers themselves.

[0030] As previously discussed, the forward channel 109 seeks maximum assurance and minimum delay when providing safety signaling from the safety operator panel 102 to the remote interface 104. Therefore, in a preferred embodiment, the forward channel 109 uses a continuous end-to-end optical fiber 106 without a CW optical signal, in-line optical amplifier, or repeater, and / or does not utilize software, computer, or coding to provide voltages 122, 124 and the first optical signal 120 between the safety operator panel 102 and the remote interface 104. In contrast, the backhaul channel 126 does not provide actual safety signaling and instead reports the QoS and / or other attributes of the forward channel 109, so the backhaul channel may, from time to time, use modulated optical signals and software or coding along the backhaul channel.

[0031] Referring further to Figure 1, in some embodiments, the SSOF system 100 may further include one or more network communication channels 134, 136 utilizing a second optical fiber 138 (indicated as "fiber 0" in Figure 1) extending between the safety operator panel 102 and the remote interface 104. Such network communication channels 134, 136 are typically used to transmit normal messages between the safety operator panel 102 and the remote interface 104 (i.e., not safety signaling). While some embodiments may utilize unidirectional communication on the network communication fiber 138, a typical embodiment, as shown in Figure 1, utilizes bidirectional communication with two channels 134, 136 to enable two-way network communication between the safety operator panel 102 and the remote interface 104.

[0032] The network communication channels typically utilize a second optical fiber 138 operably connected between a first network VTLC 140 at the safety operator panel 102 and a first network LTVC 142 located at the remote interface 104 providing an outbound channel 134, and between a second network VTLC 144 located at the remote interface and a second network LTVC 146 located at the safety operator panel providing an inbound channel 136. The first network VTLC 140 is configured to output a first optical signal 145 having a predetermined first optical frequency / wavelength (e.g., frequency "A") to carry outbound network messages to the first network LTVC 142. The second network VTLC 144 is configured to output a second optical signal 147 having a predetermined second optical frequency / wavelength (e.g., frequency "B") to return inbound network messages to the second network LTVC 146. In some embodiments, the network VTLC and LTVC devices required to operate outbound channel 134 and inbound channel 136 on a single fiber 138 can be provided by a pair of BiDi modular transceivers. A first network BiDi modular transceiver 148 located on the operator panel 102 can provide the first network VTLC 140 and the second network LTVC 146, and a second network BiDi modular transceiver 150 located on the remote interface 104 can provide the second network VTLC 144 and the first network LTVC 142. In preferred embodiments, the network communication channels 134 and 136 utilize an encoded Ethernet protocol, such as TCP / IP, for the transmission of bidirectional messages. Network transceivers 152 may be provided at each end of the network communication channels 134 and 136 to handle the encoding, decoding, routing, etc., of network messages.Each network transceiver 152 can be operationally connected to the operator control circuit 114 in the safety operator panel 102, to the remote interface control circuit 118 in the remote interface 104, and / or to an external network port 154 (e.g., an Ethernet jack) located on the safety operator panel and the remote interface.

[0033] When the safety operator panel 102 and the remote system interface 104 are connected by an optical fiber 106, the SSOF system 100 can operate to perform at least one channel of safety signaling as follows: A) To signal the safety VOTE status from the safety operator panel 102, a predetermined first voltage 122 is input to the first VTLC 110, causing the first VTLC to generate a first optical signal 120, which is then propagated to the operator end of the optical fiber 106. The predetermined first voltage 122 can be generated by setting the HMI 116 on the safety operator panel 102 to a setting corresponding to the VOTE status. B) The first optical signal 120 is transmitted through the optical fiber 106 until it reaches the remote end, where the first optical signal is received by the first LTVC 112, which causes the first LTVC to output a predetermined second voltage 124. C) Upon receiving a predetermined second voltage 124 at the remote system interface 104, the remote safety status is set to VOTE, and this status is passed to the remote system 108. This can be considered as open-loop safety signaling of the VOTE signal from the safety operator panel 102 to the remote system interface 104. When the predetermined second voltage 124 is not received at the remote interface 104, the remote interface control circuit 118 sets the remote safety status to NO VOTE, and this status is passed to the remote system 108. D) Optionally, the remote system interface 104 may be further configured to include a safety latch subcircuit 125. An interruption of a predetermined second voltage 124 in the remote system interface 104 triggers the activation of the safety latch subcircuit 125, which changes the safety status to NO VOTE (regardless of subsequent second voltages 124) until the SSOF system is reset by the operator. E) Optionally, the remote interface 104 may be further configured to confirm the remote safety status by transmitting a second optical signal 127 from a second VTLC 128 on the remote interface to a second LTVC 130 on the operator panel 102, the second optical signal which can indicate the current safety status of VOTE or NO VOTE on the remote interface on the safety operator panel.

[0034] Referring here to Figure 2, a multi-channel SSOF system 200 is shown according to another embodiment, which provides three forward safety channels, namely 109a, 109b, and 109c, as well as bidirectional network communication channels 134, 136 between the safety operator panel 102 and the remote interface 104. The multi-channel SSOF system 200 can be used for safety signaling of weapon systems, such as high-energy laser weapon systems (HELWS), but the SSOF system is not limited to such uses. In the exemplary embodiment, each forward channel 109 is transmitted via a separate optical fiber 106 using a separate optical signal, as follows: A first forward channel 109a is transmitted over optical signal 120a via optical fiber 106a ("Fiber 1" in Figure 2) and is dedicated to carrying a value of the "NOT ABORT" input, which must have either status=VOTE or status=NOT VOTE; a second forward channel 109b is transmitted over optical signal 120b via optical fiber 106b ("Fiber 2" in Figure 2) and is dedicated to carrying a value of the "HEL ARM" input, which must have either status=VOTE or status=NOT VOTE; a third forward channel 109c is transmitted over optical signal 120c via optical fiber 106c ("Fiber 3" in Figure 2) and is dedicated to carrying a value of the "TIL ARM" input, which must have either status=VOTE or status=NOT VOTE. In the illustrated embodiment, each of the optical signals 120a, 120b, and 120c has the same predetermined first optical frequency / wavelength (frequency "A"), but in other embodiments, the optical signals 120a, 120b, and 120c may have different optical frequencies / wavelengths on different optical fibers. Although not required, in the illustrated embodiment, each of the optical fibers 109a, 109b, and 109c also transmits their respective backhaul channels 126a, 126b, and 126 using their respective optical signals 127a, 127b, and 127c.Each backhaul channel 127a, 127b, and 127c can be used to transmit QoS or other information relating to its respective associated forward channel or other aspect of the system. In the illustrated embodiment, each of the second optical signals 127a, 127b, and 127c uses the same predetermined second optical frequency / wavelength (frequency "B"). However, in other embodiments, each of the second optical signals can use a different optical frequency / wavelength, as long as the respective first and second optical signals on the same optical fiber have different optical frequencies / wavelengths from each other.

[0035] Referring further to Figure 2, each forward channel 109 of the SSOF system 200 uses a first VTLC and a first LTVC, and each backhaul channel (if any) uses a second VTLC and a second LTVC, as previously described in relation to fiber 1 in Figure 1. This configuration for each of fiber 1, fiber 2, and fiber 3 is substantially similar to that described in relation to fiber 1 in Figure 1. In the illustrated embodiment of Figure 2, each of the first VTLC and second LTVC is part of a first BiDi transceiver module 132 located on the safety operator panel 102, and each of the second VTLC and first LTVC is part of a second BiDi transceiver module 134 located on the remote interface 104. Details of each forward channel 109 and each backhaul channel 126 within the SSOF system 200 are substantially similar to those described for the forward channel 109a and backhaul channel 126a of "fiber 1" in Figure 1.

[0036] Referring further to Figure 2, in the illustrated embodiment, the bidirectional network channels 134 and 136 of the SSOF system 200 are carried by an optical fiber 138 ("fiber 0" in Figure 2). One optical signal 145 is used for the outgoing network channel 134, and a second optical signal 147 is used for the incoming network channel 136. The VTLC and LTVC of channels 134 and 136 may be separate or provided by BiDi transceiver modules 148 and 150. The details of the bidirectional network channels 134 and 136 of the SSOF system 200 are substantially similar to those of the network channels 134 and 136 described in relation to fiber 0 in Figure 1.

[0037] Referring here to Figures 3 to 6, an embodiment of a safety operator panel for an SSOF system is shown in a different aspect. The safety operator panel 302 is suitable for use in multi-channel SSOF systems such as SSOF system 200, which provides three forward safety channels and a bidirectional network communication channel between the safety operator panel 302 and the remote interface 104. Different safety states can be associated with each forward channel of the SSOF system.

[0038] Referring first to Figure 3, panel 302 includes a rectangular case 304 having an HMI 116 on its front 306. The illustrated panel 302 is suitable for setting the safety states of the following variables: NOT ABORT, HEL ARM, and TIL ARM. Each can be set to status=VOTE or status=NO VOTE. The HMI 116 includes a push button 117b' for setting the NOT ABORT variable, a first switch 117a'' for setting the HEL ARM variable, and a second switch 117a'''' for setting the TIL ARM variable. Panel 302 may further include indicator lights to show the settings of the HMI buttons and switches. In the illustrated embodiment, when switch 117b' is moved to set the NOT ABORT variable to status=VOTE, light 117c' illuminates, and when the switch is set to status=NO VOTE, light 117c' does not illuminate. When switch 117a'' moves to set the HEL ARM variable to status=VOTE, light 117c'' illuminates, and when the switch is set to status=NO VOTE, light 117c'' does not illuminate. When switch 117a'' moves to set the TIL ARM variable to status=VOTE, light 117c''' illuminates, and when the switch is set to status=NO VOTE, light 117c''' does not illuminate. A network outlet jack 154 is located on the right side 308 of case 304. A power switch 310, a power indicator light 312, and data ports 314 and 316 are located on the top surface 318 of case 304.

[0039] Referring here to Figure 4, the left side 320 of case 304 is shown to include fiber optic jacks 322', 322''', and 322''' for connecting optical fibers 120a (i.e., "fiber 1"), 120b (i.e., "fiber 2"), and 120c (i.e., "fiber 3") to bidirectional SFP transceivers located within panel 302, respectively. Also shown is a network fiber jack 326 for connecting network optical fiber 138 (i.e., "fiber 0") to a network bidirectional SFP transceiver located within panel 302. Adjacent to each fiber optic jack 322', 322'', and 322''' are associated QoS indicator lights 324, which illuminate to indicate the QoS status of the optical fiber and its optical signal.

[0040] Referring here to Figures 5 and 6, the internal configuration of the safety operator panel 302 is shown. Bidirectional SFP transceivers 132a, 132b, and 132c corresponding to the fiber optic jacks 322', 322'', and 322'''' are shown operably connected to the control circuit 114. The bidirectional SFP transceivers 132a, 132b, and 132c transmit forward channels 109a, 109b, and 109c for safety signaling and also receive associated backhaul channels 126a, 126b, and 126c to report QoS. Also shown is a network bidirectional SFP transceiver 148, which is operably connected by lead 328 to the network optical network fiber jack 326 and operably connected to the network transceiver control board 152. The network transceiver board 152 may be connected to the control circuit 114 or may be a standalone control circuit. The network transceiver board 152 is operationally connected to the network output jack 154 by lead 330.

[0041] While preferred embodiments have been described in detail, it should be understood that various modifications, substitutions, and alterations can be made without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. It is a safety signaling system, A first voltage-optical converter (VTLC) located on the operator panel, configured to output a first optical signal of a predetermined first optical frequency only when it receives a predetermined first voltage indicating a first operator safety condition set to a first value, A first optical fiber, which receives the first optical signal output by the first VTLC and is operably connected at its first end to the first VTLC so as to propagate the first optical signal to the second end, A first optical voltage converter (LTVC) located at a remote interface, which is operably connected to the second end of the first optical fiber to receive the first optical signal, and is configured to output a predetermined second voltage only when the first optical signal is received, A remote interface control circuit located at the remote interface, which is operably connected to the first LTVC to receive the predetermined second voltage when the first LTVC outputs the voltage, and is configured to set a first receiving safety condition to a first value when the predetermined second voltage is received, Equipped with, Thereafter, the first optical signal provides a first forward channel, As a result, the first receiving safety condition set to the first value in the remote interface control circuit determines that the first operator safety condition is currently set to the first value. A safety signaling system in which the remote interface control circuit uses the first received safety condition to determine the current value of the first remote safety condition.

2. The safety signaling system according to claim 1, wherein the current value of the first remote safety condition is transmitted to the remote system by the remote interface control circuit.

3. The safety signaling system according to claim 1, wherein the first optical signal is a continuous wave (CW) signal.

4. The safety signaling system according to claim 3, wherein no software, computer, and coding are used to transmit the first voltage, the first optical signal, and the second voltage between the operator panel and the remote interface.

5. The safety signaling system according to claim 1, wherein the remote interface control circuit sets the current value of the first remote safety condition to the current value of the first received safety condition.

6. The remote interface control circuit further comprises a fault latch subcircuit operably mounted on the first LTVC to monitor the second voltage, The fault latch subcircuit is configured to output a fault value to the remote interface control circuit when it detects an interruption in the predetermined second voltage. The remote interface control circuit is further configured to set the current value of the first remote safety condition to a second value when it receives the fault value from the fault latch subcircuit, regardless of the current value of the first receive safety condition. The safety signaling system according to claim 1, wherein the remote interface control circuit is further configured to hold the current value of the first remote safety condition to the second value until the fault latch subcircuit is reset.

7. A second VTLC is located at the remote interface, the second VTLC is configured to output a second optical signal of a predetermined second optical frequency, the second optical frequency being different from the first optical frequency, and the second optical signal transmits the quality of service (QoS) attribute of the first forward channel. The first optical fiber is operably connected to the second VTLC at its second end so as to receive the second optical signal output by the second VTLC and to propagate the second optical signal to the first end, The system further comprises a second LTVC located on the operator panel, which is operably connected to the first end of the first optical fiber to receive the second optical signal and is configured to output a QoS voltage indicating the QoS attribute of the first forward channel, The safety signaling system according to claim 1, wherein the second optical signal provides a first backhaul channel.

8. The first VTLC and the second LTVC are provided by a first bidirectional modular transceiver located on the operator panel. The safety signaling system according to claim 7, wherein the second VTLC and the first LTVC are provided by a second bidirectional modular transceiver located at the remote interface.

9. The operator panel further comprises a third VTLC, the third VTLC configured to output a third optical signal of a predetermined third optical frequency indicating a network message. The second optical fiber is operably connected at its first end to the third VTLC so as to receive the third optical signal output by the third VTLC and to propagate the third optical signal to its second end. A third LTVC is located at the remote interface, and the third LTVC is operably connected to the second end of the second optical fiber to receive the third optical signal, and the third LTVC is configured to output a third voltage indicating the network message when it receives the third optical signal. A fourth VTLC is located at the remote interface and is configured to output a fourth optical signal of a predetermined fourth optical frequency, the fourth optical frequency being different from the third optical frequency, and the fourth optical signal transmits a different network message. The second optical fiber is operably connected at its second end to the fourth VTLC so as to receive the fourth optical signal output by the fourth VTLC and to propagate the fourth optical signal to its first end. A fourth LTVC is located on the operator panel, and the fourth LTVC is operably connected to the first end of the second optical fiber to receive the fourth optical signal, and the fourth LTVC is configured to output a different network voltage indicating the other network message. The safety signaling system according to claim 1, wherein the third and fourth optical signals together provide a bidirectional pair of network communication channels.

10. The third VTLC and the third LTVC are provided by a third bidirectional modular transceiver located on the operator panel. The safety signaling system according to claim 9, wherein the fourth VTLC and the fourth LTVC are provided by a fourth bidirectional modular transceiver located at the remote interface.

11. It is a safety signaling system, It is an operator panel, A human-machine interface (HMI) for setting the value of the first operator safety condition to one of status = VOTE and status = NO VOTE. A first bidirectional optical transceiver configured to connect to a first optical fiber, A second bidirectional optical transceiver configured to connect to a second optical fiber, and The operator panel includes an operator panel control circuit operably connected between the HMI and the first bidirectional optical transceiver, the panel control circuit activates the first bidirectional optical transceiver to transmit a continuous wave (CW) optical signal to a connected first optical fiber only while the HMI is setting the value of the first operator safety condition to status = VOTE. It is a remote interface, A third bidirectional optical transceiver configured to connect to the first optical fiber, A fourth bidirectional optical transceiver configured to connect to the second optical fiber, and The remote interface includes a remote interface control circuit operably connected to the third bidirectional optical transceiver, the interface control circuit setting the value of a first receive safety condition to status = VOTE only while the CW optical signal is received by the third bidirectional optical transceiver, A safety signaling system in which the remote interface control circuit uses the value of the first received safety condition to determine the current value of the first remote safety condition.

12. A first network interface circuit is located on the operator panel and is operably connected to the third bidirectional optical transceiver, A second network interface circuit is located at the remote interface and is operably connected to the fourth bidirectional optical transceiver, Furthermore, The safety signaling system according to claim 11, wherein the third and fourth bidirectional transceivers are configured to transmit network messages to each other via a connected second optical fiber and to relay the network messages to and from an external source.

13. The remote interface control circuit further comprises a latch subcircuit operably mounted on the second bidirectional optical transceiver to monitor the received CW optical signal, The latch subcircuit is configured to output a fault value to the remote interface control circuit when it detects an interruption in the received CW optical signal. The remote interface control circuit is further configured to set the current value of the first remote safety condition to status = NO VOTE when it receives the fault value from the latch subcircuit, regardless of the current value of the first receive safety condition. The safety signaling system according to claim 12, wherein the remote interface control circuit is further configured to hold the current value of the first remote safety condition at status = NO VOTE until the latch subcircuit is reset.

Images