JP2008304203A - Analog input module and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an analog input module allowing connection of a potentiometer in addition to sensors by some of a thermocouple, three-wire type or four-wire type thermometric resistors, a current output and a voltage output. <P>SOLUTION: The sensors by some of the thermocouple 10, three-wire type or four-wire type thermometric resistors 8, 9, current output 11 and voltage output 12 are connected selectively to four input terminals 1-A to 1-D, and input processing corresponding to an input specification is performed according to the state of the three-wire type thermometric resistors 8 connected to the input terminals 1-A to 1-D as the sensor or the potentiometer 13 is connected thereto. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an analog input module to which an analog signal from a temperature sensor, other sensors, or the like is input, and a device including the analog input module.

Conventionally, in addition to a sensor such as a thermocouple or a resistance temperature detector that detects temperature, there is an analog input circuit that can connect a current output or voltage output sensor that detects other physical quantities such as pressure and flow rate (for example, , See Patent Document 1).
JP 2004-279171 A

  However, in the conventional analog input circuit, although the same three terminals are used, the voltage level is different, so that there is no one that can selectively connect a three-wire temperature measuring resistor and a potentiometer.

  Furthermore, depending on the application, it is desirable to be able to connect a 4-wire resistance thermometer capable of detecting temperature with higher accuracy than a 3-wire resistance thermometer.

  The present invention has been made in view of the above points, and can be connected to a potentiometer in addition to a thermocouple, three-wire or four-wire temperature measuring resistor, current output, and voltage output sensor. It is an object of the present invention to provide an analog input module and a device including the analog input module.

  (1) The analog input module of the present invention includes four input terminals to which a thermocouple, a three-wire type or a four-wire type resistance temperature detector, and a sensor based on any one of a current output and a voltage output are selectively connected. An analog input module for converting an analog input from the sensor into a digital signal, wherein the potentiometer can be selectively connected to the input terminal as the sensor, and the three-wire temperature measuring resistor is connected to the input terminal. Depending on whether a body is connected or the potentiometer is connected, a corresponding input process is performed.

  According to the analog input module of the present invention, since the corresponding input processing is performed depending on whether a three-wire resistance thermometer is connected or a potentiometer is connected, the same three-terminal three-wire measurement is performed. It is possible to selectively connect a temperature resistor or a potentiometer. Further, when high accuracy is required for temperature detection, it is also possible to connect a four-wire temperature measuring resistor.

  (2) In another embodiment of the analog input module of the present invention, a plurality of sets of the four input terminals are provided.

  According to this embodiment, since a plurality of sets of four input terminals for connecting various sensors are provided, a plurality of different types of sensors can be connected.

  (3) A device according to the present invention includes the analog input module according to (1) or (2), and sends the digital signal to a CPU unit constituting a programmable controller.

  According to this invention, it is suitable as an analog input unit which comprises a programmable controller.

  (4) The device of the present invention includes the analog input module according to (1) or (2), and is based on a temperature detected by the thermocouple or the resistance temperature detector from the analog input module and a target temperature. The control output is given so that the detected temperature becomes the target temperature.

  According to the present invention, it is suitable as a temperature controller.

  According to the present invention, it becomes possible to selectively connect a three-wire resistance thermometer or a potentiometer, and when high accuracy is required for temperature detection, a four-wire resistance thermometer Can also be connected.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 and FIG. 2 are a front view and a side view showing an analog input unit as a device including an analog input module according to one embodiment of the present invention.

  This analog input unit 1 constitutes a PLC (programmable controller) together with a CPU unit, an output unit, a power supply unit, etc. (not shown). As shown in the schematic configuration diagram of FIG. 3, an analog input module 2 according to the present invention is provided. A CPU 3, a custom IC 4, and a bus connector 5.

As shown in FIGS. 1 and 2, the analog input unit 1 is equipped with a terminal block 6 of the analog input module 2 on the front side, and on the back side with other units as shown in FIG. A connector part 7 for connection is provided.
The analog input module is configured as a module board with electronic parts and connectors mounted on a board and a terminal block.

  As shown in FIG. 1, the plurality of terminals of the terminal block 6 are arranged in two rows on the left and right sides, with 11 terminals on the right A row and 10 terminals on the left B row. Various sensors are connected.

  FIG. 4 is a diagram showing a connection relationship between each terminal of the terminal block 6 and various sensors.

  In this embodiment, it has a 4-channel (CH) configuration with four sets of four terminals for connecting various sensors, and the four terminals A2 to A5 in the right A row are connected to channel 1 (input). 1) to the first to fourth terminals 1-A to 1-D, and the four terminals B2 to B5 in the left B row are the first to fourth terminals 2-A to 2 of the channel 2 (input 2). 2-D, the four terminals A6 to A9 in the right A column become the first to fourth terminals 3-A to 3-D of the channel 3 (input 3), and the four terminals B6 in the left B column To B9 are the first to fourth terminals 4-A to 4-D of the channel 4 (input 4).

  The four first to fourth terminals 1-A to 1-D, 2-A to 2-D, 3-A to 3-D, and 4-A to 4-D of each channel are as described later. One of a three-wire temperature measuring resistor 8, a four-wire temperature measuring resistor 9, a thermocouple 10, a current output sensor 11 that outputs a DC current, a voltage output sensor 12 that outputs a DC voltage, and a potentiometer 13. Can be selectively connected.

  The upper end side terminals A1 and B1 and the lower end side terminals A10 and B10 are terminals CJ2 +, CJ2-, CJ1 +, CJ1- to which temperature sensing elements for cold junction compensation are respectively connected.

  Since the input of 4 channels is possible in this way, for example, as shown in FIG. 5, a different sensor, for example, input 1, is provided for each input of input 1 (1CH) to input 4 (4CH). It is also possible to connect the thermocouple 10, the potentiometer 13 to the input 2, the three-wire or four-wire temperature measuring resistors 8 and 9 to the input 3, and the current output sensor 11 to the input 4. It is.

  FIG. 6 is a schematic configuration diagram of the analog input module 2.

  The analog input module 2 of this embodiment includes a connector 14 for connection to the CPU 3 in FIG. 3 described above, a channel switching circuit 15 for switching each channel, and the module is an analog input module or other A module recognition circuit 22 for recognizing whether the module is a module and an input processing unit 16 corresponding to each channel are provided. The input processing unit 16 of each channel (CH1 to CH4) includes an input circuit 17 to which inputs from various sensors are given, an A / D converter 18 that converts an analog signal from the input circuit 17 into a digital signal, and an insulation circuit 19, and the insulating circuit 19 includes a power supply circuit 20 and a constant voltage circuit 21.

  FIG. 7 is a circuit diagram of a main part of the input processing unit 16 of FIG. 6, and representatively shows the configuration of one channel.

  The input processing unit 16 includes an A / D converter 23 and an A / D converter 24 that constitute the A / D converter 18 described above.

  The A / D converter 23 outputs a switch switching signal corresponding to the type of sensor to be connected, controls the switching of the first and second analog switches 25 and 26, and controls the on / off of the optical MOSFET 27, The input analog signals from the various sensors are converted into digital signals and sent to the CPU 3 via the coupler 28. On the other hand, according to the input from the CPU 3, the switch switching signal and the first and second currents are input. Control of each part such as the sources 29 and 30 is performed.

  The A / D converter 24 converts the analog input from the temperature-sensitive element 31 for cold junction compensation at the time of temperature detection by the thermocouple 10 into a digital signal and sends it to the CPU 3 via the coupler 28.

  Next, each case where various sensors are connected will be described by taking channel 1 as an example.

(A) 4-wire RTD As shown in FIG. 8, the 4-wire RTD 9 is connected to the first to fourth terminals 1-A to 1-D, and the sensor type Is input to a CPU unit (not shown) and data indicating that the 4-wire resistance thermometer 9 is connected to the analog input unit 1 from the CPU unit. Become.

  As a result, a high-level switch switching signal is output from the output terminal PSW of the A / D converter 23, and the switching contact of the first analog switch 25 is switched to the first current source 29 side by this switch switching signal. The switching contact of the second analog switch 26 is open, and the optical MOSFET 27 is turned on.

  As a result, the current from the first current source 29 flows to the ground via the temperature measuring resistor 9, the optical MOSFET 27, and the reference voltage detection resistor 32 via the first analog switch 25.

  The voltage from the resistance temperature detector 9 is taken in by analog input terminals AIN2 + and AIN2- of the A / D converter 23, and the reference voltage is taken in by reference voltage input terminals REFIN2 + and REFIN2- and converted into a digital signal. To the CPU 3 described above, and the CPU 3 performs measurement processing and the like.

  Note that the two diodes 33 and 34 are connected to the second terminal 1-B in the forward direction, but the current from the first current source 29 flows because the sum of the forward voltages is large. Can be prevented.

(B) Three-wire RTD As shown in FIG. 9, the three-wire RTD 8 includes first, third, and fourth terminals 1-A, 1-C, 1-D. The user sets and inputs the sensor type.

  As a result, a high-level switch switching signal is output from the output terminal PSW of the A / D converter 23, and the switching contact of the first analog switch 25 is set by this switch switching signal as in the case of the above-described four-wire system. The first current source 29 is switched, the switching contact of the second analog switch 26 is opened, and the optical MOSFET 27 is turned on.

  In the three-wire resistance thermometer 8, the current from the first current source 29 is canceled in order to cancel the influence of the conductor resistance connected to the third and fourth terminals 1 -C and 1 -D. Is supplied to the ground via the analog switch 25, the resistance temperature detector 8, the optical MOSFET 27, and the reference voltage detection resistor 32, while the current from the second current source 30 is supplied to the conductor, the optical MOSFET 27, and the reference voltage detection resistor 32. Through the ground.

  The voltage from the resistance temperature detector 8 is taken in by the analog input terminals AIN1 + and AIN1- of the A / D converter 23, and the reference voltage is taken in by the reference voltage input terminals REFIN2 + and REFIN2- and converted into a digital signal. And the CPU 3 performs measurement processing and the like.

  The measurement process by the CPU 3 is a process corresponding to the three-wire resistance thermometer 8 as described later.

(C) Potentiometer As shown in FIG. 10, the potentiometer 13 is connected to the first, third, and fourth terminals 1-A, 1-C, and 1-D, and the user inputs the setting of the sensor type. To do.

  As a result, a high-level switch switching signal is output from the output terminal PSW of the A / D converter 23, and the first analog signal is output by this switch switching signal as in the case of the above-described three-wire temperature measuring resistor 8. The switching contact of the switch 25 is switched to the first current source 29 side, the switching contact of the second analog switch 26 is opened, and the optical MOSFET 27 is turned on.

  The current from the first current source 29 is supplied to the ground via the analog switch 25, the potentiometer 13, the optical MOSFET 27, and the reference voltage detection resistor 32, while the current from the second current source 30 is supplied to the potentiometer 13, the optical MOSFET 27. The current is supplied to the ground via the reference voltage detection resistor 32.

  The voltage from the potentiometer 13 is taken in by the analog input terminals AIN1 + and AIN1- of the A / D converter 23, and the reference voltage is taken in by the reference voltage input terminals REFIN2 + and REFIN2- and converted into a digital signal. The CPU 3 performs measurement processing and the like.

  Since the potentiometer 13 has the same connection as the above-described three-wire temperature measuring resistor 8, the CPU 3 depends on whether the potentiometer 13 or the three-wire temperature measuring resistor 8 is connected. The corresponding measurement process is performed.

  FIG. 11 is a flowchart for explaining measurement processing by the CPU 3.

  First, it is determined whether it is a potentiometer 13 or a three-wire resistance thermometer 8 according to the user's input type setting (step n1), and if it is a potentiometer 13, the input specifications for the potentiometer are set. The calibration value, inclination, and offset are set (step n2), and the A / D count value is calculated based on the specifications (step n3). In step n1, if the resistance thermometer 8 is a three-wire type RTD, the calibration value, slope, and offset of the input specifications for the three-wire RTD are set (step n4). The D count value is calculated (step n5).

  As described above, since the processing is performed in accordance with the specifications according to the potentiometer 13 and the three-wire temperature measuring resistor 8, the same input circuit can be shared by the potentiometer and the three-wire temperature measuring resistor having different voltage levels. it can.

(D) Thermocouple As shown in FIG. 12, the thermocouple 10 is connected to the first and third terminals 1-A and 1-C, and the user sets and inputs the sensor type.

  As a result, a low-level switch switching signal is output from the output terminal PSW of the A / D converter 23, and the switching contact of the first analog switch 25 is switched to the power supply voltage AVDD side by this switch switching signal. The reason why the power supply voltage AVDD is connected in this way is to enable detection when the thermocouple 10 is disconnected.

  The voltage generated in the thermocouple 10 is taken in by analog input terminals AIN1 + and AIN1- of the A / D converter 23, converted into a digital signal, given to the CPU 3 via the coupler 28, and the CPU 3 performs measurement processing and the like.

  In the cold junction compensation, the input from the two temperature sensing elements 31 is converted into a digital signal by the A / D converter 24 and given to the CPU 3 via the coupler 28.

(E) Voltage output sensor As shown in FIG. 13, the voltage output sensor 12 is connected between the third and fourth terminals 1-C and 1-D, and the user sets and inputs the sensor type.

  As a result, a low-level switch switching signal is output from the output terminal PSW of the A / D converter 23, and the switching contact of the second analog switch 26 is opened from the open side to the input terminal of the A / D converter 23 by this switch switching signal. And the optical MOSFET 27 is turned off.

  The voltage of the voltage output sensor 12 is taken in by the analog input terminals AIN3 + and AIN3− of the A / D converter 23 via the voltage detection resistors 35 and 36, converted into a digital signal, given to the CPU3 via the coupler 28, and the CPU3. Measurement processing and the like are performed.

(F) Current output sensor As shown in FIG. 14, the current output sensor 11 is connected to the 1-B and 1-C between the second and third terminals, and the user sets and inputs the sensor type.

  The output current of the current output sensor 11 is captured by the analog input terminals AIN6 + and AIN6- of the A / D converter 23 via the current detection resistor 37, converted into a digital signal, given to the CPU3 via the coupler 28, and measured by the CPU3. Processing is performed.

  As described above, any of the inputs of the thermocouple, the 3-wire type or the 4-wire type resistance temperature detector, the potentiometer, the current output sensor, the voltage output sensor, and the potentiometer is taken in by the first to fourth terminals. It becomes possible.

(Other embodiments)
In the above-described embodiment, the present invention is applied to the analog input unit that constitutes the programmable controller. However, the present invention is not limited to the analog input unit, and the present invention is not limited to the analog input unit of the temperature controller. The analog input module may be used.

  The present invention is useful for an analog input unit constituting a programmable controller.

It is a front view of the analog input unit which concerns on embodiment of this invention. It is a side view of FIG. It is a block diagram which shows schematic structure of an analog input unit. It is a figure which shows the connection of the terminal block of an analog input unit, and various sensors. It is a figure which shows the example of a connection of the sensor with respect to each input of an analog input unit. It is a figure which shows schematic structure of an analog input module. It is a block diagram of the input processing part of an analog input module. It is a figure corresponding to FIG. 7 which shows the state which connected the 4-wire type resistance temperature sensor. It is a figure corresponding to FIG. 7 which shows the state which connected the 3-wire type resistance temperature sensor. It is a figure corresponding to FIG. 7 which shows the state which connected the potentiometer. It is a flowchart which shows a process when a potentiometer or a 3-wire type resistance thermometer is connected. It is a figure corresponding to FIG. 7 which shows the state which connected the thermocouple. It is a figure corresponding to FIG. 7 which shows the state which connected the voltage output sensor. It is a figure corresponding to FIG. 7 which shows the state which connected the current output sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Analog input unit 2 Analog input module 6 Terminal block 8 3-wire type resistance thermometer 9 4-wire type resistance thermometer 10 Thermocouple 11 Current output sensor 12 Voltage output sensor 13 Potentiometer

Claims (4)

It has four input terminals to which a thermocouple, a three-wire type or a four-wire type resistance temperature detector, a sensor with either current output or voltage output is selectively connected, and the analog input from the sensor is converted into a digital signal An analog input module to convert,
As the sensor, a potentiometer can be selectively connected to the input terminal, and the input terminal corresponds to whether the three-wire resistance thermometer or the potentiometer is connected to the input terminal. An analog input module that performs input processing.   The analog input module according to claim 1, comprising a plurality of sets of the four input terminals.   A device comprising the analog input module according to claim 1 or 2, wherein the digital signal is sent to a CPU unit constituting a programmable controller.   The analog input module according to claim 1 or 2 is provided, and the detected temperature is calculated based on a temperature detected by the thermocouple or the resistance temperature detector from the analog input module and a target temperature. A device that provides a control output so as to reach a target temperature.

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