A 485 bus temperature transmitter with intelligent link cascading and terminal detection

Abstract

The present invention discloses a temperature transmitter with intelligent link cascade and terminal detection, which integrates a temperature measuring thermocouple, a signal conditioning circuit, a cold end compensation, a microprocessor and a digital bus interface. In view of the characteristics of hull structure welding construction, a special link monitoring circuit is specially designed. On the one hand, it is used to monitor the connection status of a bus-type intelligent temperature sensor field bus, automatically confirm the temperature sensor at the end of the link, and connect to the corresponding communication link terminal resistor; on the other hand, it can realize the communication token transmission based on the hardware connection for the intelligent temperature sensor connected to the communication link, which can further improve the communication quality and reliability of information data interaction and the stability of system operation.

Description

Technical Field

[0001] The invention relates to the field of industrial communication, and in particular to a 485 bus temperature transmitter with intelligent link cascading and terminal detection. Background Art

[0002] With the further improvement of the country's requirements for hull welding quality, and the commissioning of the shipyard's hull welding full process quality tracking and analysis system and welding parameter recording, in order to further improve the company's production efficiency, ensure safe production, meet the quality management requirements of full process traceability, and ensure welding quality, it is necessary to monitor the relevant temperature parameters and heating current voltage and other process parameters in the heat treatment process after hull welding preheating in real time, incorporate them into the hull welding full process quality tracking and analysis system, use the weld number as the index, and associate all welding operation processes with the weld as the main line, implement real-time recording, supervision and analysis of the entire welding process, and comprehensively improve the hull welding quality to meet the needs.

[0003] The welding preheating post-heat temperature monitoring system detects the temperature of the entire hull welding preheating process in real time, displays it in real time on the welding preheating post-heat monitoring terminal, and uploads it to the hull welding whole process quality tracking and analysis system at the same time. The hull welding whole process quality tracking and analysis system is associated with the welding parameter monitoring data and tasks, thereby realizing the whole process supervision of the hull welding preheating post-heating process to ensure the quality of hull structure welding.

[0004] According to the heating control and monitoring requirements of the entire welding preheating and post-heating temperature, since the hull structure welding preheating and post-heating uses a heating plate to locally heat the weld, a long weld may be tens of meters long, and dozens of heating plates need to be laid to locally heat the entire weld. In order to fully understand whether the temperature of each heating section of the entire weld preheating and post-heating process meets the requirements of the welding process specifications, the temperature monitoring points need to correspond to the heating sections, and dozens of temperature measurement points also need to be set. If a conventional temperature monitoring solution is used, a large number of temperature measurement cables need to be laid at the welding construction site. On the one hand, these measurement cables may affect the on-site welding work, and on the other hand, they will increase the auxiliary workload before welding and reduce work efficiency.

[0005] At present, the hull structure welding manufacturing process has the following problems: 1) The existing system does not have a real-time and complete record of the thermal monitoring operator after welding preheating, and mainly uses manual recording to record the operation process accordingly, which may cause omissions or subsequent supplementary records. This causes the heating process to be unable to be recorded in real time and cannot be traced; 2) The on-site layout of the temperature measuring thermocouple lacks the means to ensure reliable contact between the temperature measuring element and the measured parent material, and there is a certain error between the measured temperature and the actual heating temperature; 3) After the on-site heating task begins, each heating cabinet uses a K-type thermocouple, and then 12 terminals and 1 probe are used, which makes it impossible to correctly reflect the actual situation of the entire heating temperature data, and it is impossible to accurately control the working status of the heating plate; 4) In the traditional 485 bus communication system, the slave address is usually set one by one using a dip switch or a human-machine setting method, but in the real environment networking process, the location and number of the distribution nodes of the welding temperature monitor are not fixed, so the traditional method is time-consuming and labor-intensive. Summary of the invention

[0006] In view of this, in view of the above technical problems, the present invention provides a 485 bus temperature transmitter with intelligent link cascading and terminal detection, comprising:

[0007] Temperature signal transmission unit, front-end signal processing and amplification unit, microcontroller, link monitoring unit and link testing unit;

[0008] The temperature signal transmission unit is electrically connected to the front-end signal processing and amplification unit;

[0009] The front-end signal processing and amplification unit is electrically connected to the microcontroller;

[0010] The link monitoring unit is electrically connected to the microcontroller via the communication links LKR and END;

[0011] The link test unit is electrically connected to the microcontroller via a communication link LKT;

[0012] There are multiple temperature signal transmission units, which are connected by a cascaded 485 bus and are distributedly installed near different welds of the welding operation main line;

[0013] The temperature signal transmission unit is electrically connected to the temperature monitoring terminal via the communication link A and the communication link B;

[0014] The link monitoring unit is used to obtain addresses of multiple temperature signal transmitting units;

[0015] The link test unit is used to test whether the current temperature signal transmitting unit is the last temperature signal transmitting unit.

[0016] Furthermore, the temperature signal transmitting unit includes a magnetic temperature probe and a temperature acquisition unit.

[0017] Furthermore, the magnetic temperature probe is connected to the temperature acquisition unit through a stainless steel soft sheath tube; an electrical connection line between the temperature measurement point and the temperature acquisition unit is arranged inside the stainless steel soft sheath tube.

[0018] Furthermore, a high temperature resistant magnetic steel is installed on the magnetic temperature probe, and the magnetic steel is used to reliably adsorb the magnetic temperature probe on the welded wood.

[0019] Furthermore, the temperature collection unit adopts a K-type thermocouple.

[0020] Furthermore, each temperature acquisition unit has a unique identification code; in the initial state, the temperature monitoring terminal presets the code of the temperature acquisition unit at the end of the communication link; the microcontroller initiates a cascade test request through the temperature acquisition unit at the end; the link monitoring unit obtains the address of the previous temperature acquisition unit in turn according to the address of the end temperature acquisition unit, and stores it, thereby obtaining the addresses of all temperature acquisition units.

[0021] The front-end signal processing and amplification unit includes signal filtering, signal amplification, cold end compensation and disconnection detection modules.

[0022] The beneficial effects provided by the present invention are:

[0023] 1. The organic integration of welding temperature transmitter and welding parameter information can fully reflect the welding process of the weld and lay a good foundation for the whole process management of the welding system.

[0024] 2. The use of sheet thermocouple structure and magnetic high temperature resistant probe makes the measuring point in reliable contact with the on-site welding material, and can quickly and accurately monitor the on-site welding material temperature data information.

[0025] 3. Rapidly deploy bus-type welding temperature signal transmission units, which use a special communication protocol combined with hardware circuits. It has the functions of rapid positioning and detection of on-site temperature monitoring nodes, and can quickly find the location of node temperature faults. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural diagram of a 485 bus temperature transmitter with intelligent link cascading and terminal detection of the present invention;

[0027] Figure 2 This is the connection structure diagram of the temperature signal transmission unit;

[0028] Figure 3 It is the layout point plan of the temperature signal transmission unit;

[0029] Figure 4 It is a specific circuit schematic diagram of the link detection unit;

[0030] Figure 5 It is a schematic diagram of the cascade connection relationship between communication nodes (temperature transmitter units). DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0032] Please refer to Figure 1 , a 485 bus temperature transmitter with intelligent link cascading and terminal detection, comprising the following:

[0033] Temperature signal transmission unit, front-end signal processing and amplification unit, microcontroller, link monitoring unit and link testing unit;

[0034] The temperature signal transmission unit is electrically connected to the front-end signal processing and amplification unit;

[0035] The front-end signal processing and amplification unit is electrically connected to the microcontroller;

[0036] The link monitoring unit is electrically connected to the microcontroller via the communication links LKR and END;

[0037] The link test unit is electrically connected to the microcontroller via a communication link LKT;

[0038] Please refer to Figure 2 , Figure 2 This is the connection structure diagram of the temperature signal transmission unit;

[0039] The temperature signal transmission unit includes a magnetic temperature probe (corresponding to Figure 2 The invention relates to a temperature collecting unit, wherein the temperature collecting unit adopts a K-type thermocouple probe.

[0040] There are multiple temperature signal transmission units, which are connected by a cascaded 485 bus and are distributedly installed near different welds of the welding operation main line; the temperature signal transmission unit is electrically connected to the temperature monitoring terminal through a communication link A and a communication link B;

[0041] Please refer to Figure 3 , Figure 3 It is the layout point plan of the temperature signal transmission unit.

[0042] Since the preheating or post-heating temperature of the base material to be welded is relatively high, the temperature signal transmission part cannot be directly installed on the temperature probe part. The temperature probe and the temperature signal conversion unit are separated so that the temperature signal transmission unit part can be appropriately away from the high temperature area.

[0043] The magnetic temperature probe is connected to the temperature acquisition unit through a stainless steel soft sheath tube;

[0044] The electrical connection line between the temperature measuring point and the temperature acquisition unit is laid in the stainless steel soft sheath pipe. The stainless steel soft sheath pipe can withstand the high temperature at the welding construction site and the damage to the cable caused by spatter generated during welding.

[0045] The magnetic temperature probe of the present invention is provided with high temperature resistant magnetic steel, which is used for reliably adsorbing the temperature probe on the parent material to be welded.

[0046] The temperature probe adopts a clamping mechanism to enable the temperature probe to reliably contact the base material to be welded to ensure the reliability of temperature measurement.

[0047] The temperature acquisition unit uses a K-type thermocouple, and the maximum measurement temperature can reach 1300°C. The high-temperature resistant magnetic steel uses samarium cobalt permanent magnetic steel, and the maximum working temperature can reach 350°C, which can meet the requirements of the hot temperature working range after hull welding preheating.

[0048] The link monitoring unit is used to obtain addresses of multiple temperature signal transmitting units;

[0049] Please refer to Figure 4 , Figure 4 It is a specific circuit schematic diagram of the link detection unit;

[0050] In order to facilitate the determination of the relative position of each communication node (temperature transmitter unit) on the communication link, each node is assigned a unique identification code. In the initial state, the temperature monitoring terminal can obtain the identification code of the node at the end of the communication link. The node at the end of the communication link initiates a link cascade test request to the second-to-last temperature monitoring node. After the temperature monitoring node receives the request, it communicates with the temperature monitoring terminal and sends the identification code of its temperature monitoring node. This is done in sequence to complete the cascade test of the entire communication link, obtain the identification codes of all temperature monitoring nodes on the communication link, and obtain the location information of each temperature monitoring node on the communication link.

[0051] refer to Figure 4 This part of the function is composed of the second channel of the optocoupler E1 and related resistor and capacitor components, the optoelectronic solid-state relay E2 and related components.

[0052] First, the microcontroller controls the LKCH signal to become a high level, and the photoelectric solid-state relay E2 is turned on. It is connected to the temperature monitoring node at the node above this node through the connection line of resistor R17 and terminal LNKO (that is, LNKO is high level, LNKO is connected to LKIN of the previous node, so LKIN is high level). The light-emitting diode in the second channel of the photoelectric coupler E1 in this node is electrically turned on, and the corresponding output end becomes a high level, that is, SLNK=1, and a link cascade test request is made to the microprocessor in this node. This node will communicate with the temperature monitoring terminal and report its identification code.

[0053] The temperature monitoring terminal includes a display control interface. After clicking OK in the pre-configured two-way 485 bus all heating measurement point device schematic diagram in front of the temperature monitoring terminal, the link monitoring unit will perform polling verification with each measurement point. After all measurement point devices are successfully verified, the current interface will be closed to achieve automatic enumeration of device IDs.

[0054] The core implementation of this part is that the LNKO end of the current node is connected to the LKIN end of the previous node, and the LKIN end of the previous node is connected to the LKCH end of the previous node, thereby realizing cascading (the cascading in the present invention is to cascade from the end of the communication link to the reverse direction).

[0055] Please refer to Figure 5 , Figure 5 It is a schematic diagram of the communication link cascade design of the present invention.

[0056] Here is Figure 1 , Figure 4 , Figure 5 The relevant connection ports are described in a unified manner.

[0057] LKO==LKT==LNKO、LKI==LKR==LKIN、EDO==EDKO、EDI==EDIN、END are the labels on the circuit board, where O means output and IN means input.

[0058] from Figure 5 It can be seen that the communication links are connected in a cascade manner.

[0059] The link test unit is used to test whether the current temperature signal transmitting unit is the last temperature signal transmitting unit.

[0060] The principle of the link test unit is still referenced here Figure 4The post-welding preheating temperature monitoring adopts a bus-based communication bus structure. Generally, the first communication node and the last communication node are required to be configured with terminal resistors. For the post-welding preheating temperature monitoring, due to the particularity of welding production, the temperature monitoring points are arranged according to the welding process requirements, and the temperature at the specified position of the weld is detected. Therefore, the post-welding preheating temperature monitoring points change with different welding processes and the position of the weld of the welded part. In addition to the first communication node that can be determined as the post-welding preheating temperature monitoring terminal, the end temperature monitoring node on the temperature monitoring communication link changes with the number of temperature monitoring points that need to be monitored and the position of the temperature monitoring points.

[0061] The link test unit is used to realize terminal communication node detection, thereby detecting the communication node at the end of the bus-type temperature monitoring communication bus, and automatically inputting the terminal resistance on the communication bus according to the signal state and the corresponding control strategy.

[0062] refer to Figure 4 This part of the function is composed of the first channel photoelectric coupler of the photoelectric coupler E1 and related resistor and capacitor components. If a communication node in the communication link is not the last node, the ENDO terminal is connected to the EDIN terminal of the next communication node through the communication connection cable, and the EDIN terminal inside the next communication node is connected to the reference ground GND of the power supply. Then the light-emitting diode of the channel is turned on, and the SEND terminal of this communication node outputs a high level, indicating that the communication node is not at the end of the communication link. On the contrary, the SEND terminal is a low level. The microcontroller detects the level state of the SEND terminal to identify whether the communication node is at the end of the communication link.

[0063] The front-end signal processing and amplification unit includes signal filtering, signal amplification, cold end compensation and disconnection detection modules.

[0064] The front-end signal processing and amplification part of the thermocouple mainly filters and amplifies the weak electrical signal of the thermocouple. This part of the circuit is based on a dedicated precision thermocouple amplifier. The dedicated thermocouple amplifier uses the precision thermocouple amplifier AD8497 with integrated cold junction temperature compensation function produced by AD. This thermocouple amplifier integrates a complete, precision laser wafer-adjusted K-type thermocouple signal conditioning circuit and integrated cold junction compensation function. It has high impedance differential input, independent 5mV / ℃ signal output, reference pin offset adjustment, thermocouple disconnection detection and other functions. Through different pin configurations, it can be used for set point controllers or independent Celsius temperature converters. Its input part can withstand 4kVESD and provide VS±25V overvoltage protection (OVP). The use of differential input can effectively suppress the common mode noise on the thermocouple pins. The front-end signal processing and amplification part of the thermocouple includes signal filtering, disconnection detection, cold junction compensation and signal amplification.

[0065] About signal filtering:

[0066] Due to the serious power frequency and high-frequency harmonic electromagnetic interference caused by welding operations at welding construction sites, the long lead of the thermocouple will produce an antenna effect, receiving electromagnetic interference signals from the welding construction site. In order to ensure the stable operation of the thermocouple measurement signal, a low-pass filter is configured before the input of the thermocouple amplifier. The purpose of setting the low-pass filter is to eliminate the radio frequency interference signal, because these interference signals are input to the thermocouple amplifier and may be rectified and amplified, which will appear as temperature fluctuations. Signal filtering is achieved by an RC low-pass filter composed of resistors and capacitors to complete the low-pass filtering of the common-mode and differential-mode signal parts of the thermocouple signal. To achieve signal filtering, you can select existing modules according to actual conditions.

[0067] About signal amplification:

[0068] Signal amplification is applied to the measurement of the post-heating temperature of welding preheating, and the measurement temperature range is 0℃~350℃, and the AD8497 is powered by a +5V power supply. Since the electrical signal generated by the thermocouple is very small, it must be amplified with a corresponding large gain before it can be properly sampled by the subsequent ADC. In the present invention, the -Vs of the thermocouple amplifier AD8497 is 0V, so when it corresponds to 0℃, the output voltage of the amplifier is 0.025V, which cannot achieve the measurement of temperatures less than 5℃, and the minimum measurement temperature should be greater than 5℃.

[0069] The +Vs of the thermocouple amplifier AD8497 in the circuit of the present invention adopts 5V. Considering the deviation range of the circuit power supply voltage, calculated at 5%, the maximum measured temperature can be as high as 950°C.

[0070] About cold junction compensation:

[0071] AD8497 has a built-in temperature sensor for cold-end compensation, which is used to measure the reference junction temperature of the thermocouple and eliminate its influence through compensation calculation. The cold-end compensation of AD8497 is optimized for an operating environment with a temperature of about 60°C, and the rated ambient temperature range is 25°C to 100°C.

[0072] About disconnection detection:

[0073] The output of AD8497 is a PNP transistor, and its bias current always flows out from the input terminal. A resistor R1 with a resistance of 1MΩ is configured between the TE- terminal and the reference ground GA. The configuration current of the IN- pin of the thermocouple amplifier U2 is about 25nA. When the thermocouple is broken, the input configuration current flows into the resistor R1 to generate an input voltage, so that the output voltage of the amplifier reaches the power rail voltage in the case of a thermocouple break fault. The amplifier output voltage is detected to see if it reaches the power rail voltage, thereby realizing the function of thermocouple break detection.

[0074] The beneficial effects of the present invention are: 1. The organic integration of the welding temperature transmitter and the welding parameter information can fully reflect the welding process of the weld and lay a good foundation for the whole process management of the welding system.

[0075] 2. The use of sheet thermocouple structure and magnetic high temperature resistant probe makes the measuring point in reliable contact with the on-site welding material, and can quickly and accurately monitor the on-site welding material temperature data information.

[0076] 3. Rapidly deploy bus-type welding temperature signal transmission units, which use a special communication protocol combined with hardware circuits. It has the functions of rapid positioning and detection of on-site temperature monitoring nodes, and can quickly find the location of node temperature faults.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A 485 bus temperature transmitter with intelligent link cascading and terminal detection, It is characterized in that include: Temperature signal transmission unit, front-end signal processing and amplification unit, microcontroller, link monitoring unit and link testing unit; The temperature signal transmission unit is electrically connected to the front-end signal processing and amplification unit; The front-end signal processing and amplification unit is electrically connected to the microcontroller; The link monitoring unit is electrically connected to the microcontroller via the communication links LKR and END; The link test unit is electrically connected to the microcontroller via a communication link LKT; There are multiple temperature signal transmission units, which are connected by a cascaded 485 bus and are distributedly installed near different welds of the welding operation main line; The temperature signal transmission unit is electrically connected to the temperature monitoring terminal via the communication link A and the communication link B; The link monitoring unit is used to obtain addresses of multiple temperature signal transmitting units; The link test unit is used to test whether the current temperature signal transmission unit is the last temperature signal transmission unit; The temperature signal transmission unit includes a magnetic temperature probe and a temperature acquisition unit; The magnetic temperature probe is connected to the temperature acquisition unit through a stainless steel soft sheath tube; an electrical connection line between the temperature measurement point and the temperature acquisition unit is arranged inside the stainless steel soft sheath tube; The magnetic temperature probe is installed with a high temperature resistant magnetic steel, which is used to reliably adsorb the magnetic temperature probe on the welded wood; Each temperature collection unit has a unique identification code; In the initial state, the temperature monitoring terminal presets the code of the temperature acquisition unit at the end of the communication link; The microcontroller initiates a cascade test request through the terminal temperature acquisition unit; the link monitoring unit obtains the address of the previous temperature acquisition unit in sequence according to the address of the terminal temperature acquisition unit, and stores it, thereby obtaining the addresses of all temperature acquisition units.

2. A 485 bus temperature transmitter with intelligent link cascading and terminal detection as claimed in claim 1, Features: The temperature collection unit adopts a K-type thermocouple.

3. A 485 bus temperature transmitter with intelligent link cascading and terminal detection as claimed in claim 1, Features: The front-end signal processing and amplification unit includes signal filtering, signal amplification, cold end compensation and disconnection detection modules.

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