JPH01140309A - Positioner with communication function - Google Patents

Abstract

PURPOSE:To realize bidirectional communication with the min. number of lines and to perform remote monitor and adjustment by providing a communication terminal to be connected to a communication equipment provided at the outside on a communication processing part, and performing a transmission and a reception operations by voltage change between the communication terminals. CONSTITUTION:A signal corresponding to the quantity of state of a control valve 3 (valve lift) is outputted from an arithmetic processing part 13, and the signal can be transmitted from the communication terminals 16 and 17 of the communication processing part 15. In such a case, communication from the communication processing part 15 to the communication equipment 10 is performed by detecting the voltage change between the communication equipment 10 connected to the communication terminals 16 and 17 and the communication terminals 16 and 17. Meanwhile, when a terminal voltage at the communication equipment 10 changes, the communication processing part 15 detects the fact, and the communication from the communication equipment 10 to the communication processing part 15 is performed. In such a way, it is possible to perform the bidirectional communication with the min. number of lines, and also, to perform the remote monitor or the adjustment from a controller 2 side.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a positioner having a communication function.

[Prior Art] A positioner, which is a type of pneumatic servo mechanism, has the function of controlling the valve position of a control valve according to a control signal from a controller. There is also a positioner that performs arithmetic processing to generate signals No. 1 and 1 that control the drive section of the control valve.

[Problems to be Solved by the Invention] However, conventional positioners operate according to unilateral commands from the controller, which can lead to abnormalities in the positioner or control valve! If the situation or need for adjustment arises,
It was difficult for the controller to quickly detect this. Therefore, a positioner equipped with a communication function that monitors the status of equipment in the field and notifies the controller side as necessary is being considered. In addition to requiring a transmission line separate from the above, a power supply line for supplying power for communication is also required, resulting in an increase in the number of lines and the number of man-hours required for installation, which increases equipment costs.

The present invention has been made in view of the above problems, and
The purpose of the present invention is to provide a positioner that realizes bidirectional communication with a minimum number of lines and has a communication function that enables remote monitoring and adjustment.

[Means for Solving the Problems] The positioner of the present invention includes an input signal detection section that manually receives a control signal from a controller, a valve lift detection section that detects a valve lift of a control valve, and the input signal detection section and An arithmetic processing section that performs predetermined arithmetic processing based on the detection signal from the valve lift detection section and outputs a signal for controlling the drive section of the control valve, and converts the drive section control signal from the arithmetic processing section into a pneumatic signal. and an electro-pneumatic conversion unit that supplies a signal to the drive unit, and a communication processing unit that performs predetermined communication according to a signal output from the arithmetic processing unit, and the communication processing unit connects an external communication device. The device is characterized in that it has a communication terminal, and performs a transmission or reception operation by changing the voltage between the communication terminals.

[Operation] According to the above configuration, a signal corresponding to the shape B stitch (valve lift) of the control valve is output from the rA calculation processing section.

This signal can be transmitted from the communication terminal of the communication processing section. In this case, the communication device connected to one communication terminal detects a voltage change between the communication terminals, thereby performing communication from the communication processing section to the communication device. On the other hand, when the terminal voltage of 1 communication device changes, 1 communication processing section detects this and 1
Communication is performed from the communication device to the communication processing unit.

[Embodiment] FIG. 1 shows the configuration of an embodiment of the present invention. In addition to the positioning function of controlling the valve position of the control valve 3 according to the control signal from the controller 2, the positioner l has a communication function described below. have Therefore.

Positioner l has two lines 4.5 from controller 2
an input signal detection section 11 to which a control signal is input via a two-wire transmission line consisting of; a valve lift detection section 12 that detects the valve lift of the control valve 3; an arithmetic processing section 13 that performs predetermined arithmetic processing based on the detection signal of and outputs a PWM signal (pulse width signal that gives a valve lift) that controls the driving section of the control valve 3;

An electro-pneumatic conversion unit 14 converts the PWM output from the arithmetic processing unit 13 into a pneumatic signal and supplies it to the drive unit of the control valve 3.
and a communication processing unit 15 that performs predetermined communication according to the signal output from the arithmetic processing unit 13. The communication processing unit 15 has a pair of communication terminals 16 and 17, and a
The power supply (
for example.

Voltage E=24 volts) 8 is connected. This two-wire transmission line has a line resistance (for example, resistance value r=2soΩ) 9, and a communication device 1O, which will be described later, is connected between both lines.

Note that since analog signals are output from the input signal detection section 11 and the valve lift detection section 12, an A/D converter 18 converts these signals into digital signals and inputs them to the arithmetic processing section 13.
is provided.

In the above configuration, a DC signal of 4 to 20 mA is transmitted and received between the controller 2 and the input signal detection unit 11, and power for operating the positioner l is supplied from the controller 2 via the same line 4.5. be done. As the input signal detection section 11, a receiving device (Japanese Patent Laid-Open No. 257829/1993) according to a patent application filed by the same applicant is used.

In this receiving device, a first variable impedance element and a receiving impedance element are inserted in series in a two-wire transmission line, and the line voltage VL of the transmission line is made constant (to 10 volts, for example). While controlling the impedance of the first variable impedance element, a series circuit of the second variable impedance element and the impedance element is connected in parallel, and the current Ic flowing through the impedance element is made constant (to 4 mA, for example). configured to control the impedance of the second variable impedance element,
A load circuit is connected in parallel with the second variable impedance element. According to this configuration, the line current IL is 4
In the case of ~20 mA, the current IS flowing through the series circuit of the first variable impedance element and the receiving impedance element is reduced to only a signal component of 0-18 mA, without affecting the reception of the signal indicated by this current Is. A maximum of 4 mA of power supply current can be stably supplied to the load circuit.

In this way, the signal supplied from the controller 2 together with the power supply current is outputted from the input signal detection section 11 as a voltage signal of, for example, 1 to 3V by the load circuit, converted into a digital signal by the A/D converter 18, and subjected to arithmetic processing. 13.

On the other hand, the valve lift detection section 12 is composed of a known detection circuit that converts the stem displacement of the control valve 3 into 1 to 3V electricity (No. 3), and the detection signal is also converted into a digital signal by the A/D converter 18. It is converted and input to the arithmetic processing section 13.

The arithmetic processing unit 13 is composed of a microprocessor (CPU). This calculates the deviation between the digital signal supplied via the A/D converter 18, that is, the target value signal from the input signal detection section 11 and the valve lift signal from the valve lift detection section 12, and calculates the valve lift according to the deviation. It is programmed to perform the VT arithmetic operation as a conventional positioner that generates a control signal (PWM), and to control the communication operation by the communication processing section 15. Therefore, the arithmetic processing section 13.

As signals to the communication processing unit 15, the above-mentioned PWM signal and a pulse signal T! for digital communication are used. and.

It outputs a switching signal SX for switching the states of switches S1 and S3, which will be described later. Note that from the communication processing section 15, a received signal R1 through digital communication, which will be described later, is input to the arithmetic processing section 13.

The electro-pneumatic conversion unit 14 is configured with a known conversion circuit that converts the valve lift control signal output as a digital signal from the arithmetic processing unit 13 into a pneumatic pressure signal.

Next, as shown in FIG. 2, the first communication processing section 15 includes a switch S1 that inputs either the PWM signal or the pulse signal Tx sent from the first calculation processing section 13, and a switch S1 that is turned on or off depending on the input signal. It has a switch S2 that is turned on and a switch S3 that is turned on or off in response to a switching signal St from the arithmetic processing section 13. Switching signal S!
The switch S1 is activated by the pulse signal T! When setting the switch S1 to the input side of the PWM signal, the switch S3 is turned off, and when setting the switch S1 to the input side of the PWM signal, the switch S3 is turned on.

The communication processing section 15 is composed of the circuit shown in FIG. 2, and this circuit is divided into a transmitting circuit section, a receiving circuit section, and a power supply circuit section.

The oscillation circuit section connects the above-mentioned switches S2 and S3 in series via a resistor r2, connects a smoothing capacitor C1 to the switch S3, connects resistors r1 and r3 in parallel with these, and connects both resistors rl and r3. Point and resistance r2. An input circuit formed by connecting the connection point of switch S3 and +
An operational amplifier (op-amp) Al whose side (non-inverting) input terminal is connected between resistors r1 and r3 and whose one side (inverting) input terminal is at a quasi-potential (ground) of 2Jli is connected to its output terminal. It includes a connected transistor Ql and a resistor r4 connected to its emitter terminal (reference potential).

In addition to the above transistor Q1 and resistor r4, the receiving circuit section includes an operational amplifier A2 whose one side input terminal is connected to the collector of the transistor Q1 via a coupling capacitor C2, and a diode D and a resistor r5 connected to the same input terminal. , includes resistors r6 and r7 connected to the + side input terminal of operational amplifier A2, and outputs the output of operational amplifier A2 to receive signal R1.
The signal is connected to be supplied to the arithmetic processing unit 13 as a signal.

Furthermore, the power supply circuit section includes the two operational amplifiers A1 and A.
A first power supply stabilizing circuit VR, which creates a power supply voltage Vp (for example, 5 ports) to be supplied to each operational amplifier AI.
, voltage dividing resistors r1 and r3 connected to the + side input terminal of A2.
．． A constant voltage Vr applied to rQ and r7 (for example, 2.
5 volts) and a second power supply stabilizing circuit VR2.

Thus, the communication processing section 15 connects the collector terminal of the transistor Q1 and one end of the resistor r4 connected to its emitter to the communication terminals 16 and 17, respectively, and connects the transmission line 6.7 between the two terminals. A communication device IO is connected to the terminal.

The communication device 10 is a communication interface called 5FC (smart field communicator) that performs digital communication with the communication processing section 15, and is configured as shown in FIG. That is, the communication device 10 has a CPU
21, a keyboard 22, a display 23, and a transmitting/receiving circuit 24 connected thereto, a switch 25 that is turned on/off by a switching signal from this transmitting/receiving circuit 24, a current source 26 connected in series with this switch 25, and a transmitting/receiving circuit. 24 and a filter 27 connected between the current source 26 and, in use, a terminal 28 on the current source 26 side and a terminal 29 on the switch 25 side are respectively connected to the two-wire transmission line 6.7. .

Next, the operation of the above embodiment, especially the communication operation, will be explained.

First, when the communication terminals 16.17 are open, that is, when the line 6.7 and Tsushin W11O are not connected to these communication terminals, the communication processing section 15 does not operate and does not consume power. 1, a maximum of 4 mA power supply 'i [
flow is supplied. Thereby, the positioner 1 can perform the same positioning function as the conventional one.

In contrast, a line 6.7 is connected to the communication terminal 16.17, a line resistance r and a power source E are added, and the communication device 1
By connecting 0, power is supplied to the communication processing unit 15, and a first-order communication operation can be performed.

First, the switching signal S! from the arithmetic processing section 13! Therefore, when the switch S1 is set to the input terminal of the PWM signal, the switch S3 is turned on, and the switch S2 is turned on or off according to the PWM signal output from the rA calculation processing section 13.
state. As a result, the output of operational amplifier A1 changes,
The state of transistor Q1 changes and communication terminals 16 and 17
A voltage change is caused between the two. At this time, the transmitting/receiving circuit 24 of the communication device IO turns off the switch 25. Therefore, the above voltage change appears as a voltage change between the terminals 28 and 29 of the communication device 10 connected to the line 6.7, and the CPU 21 of the communication device 10 detects this via the transmitting/receiving circuit 24. As a result, the communication processing unit 15 may
Communication to 0 takes place.

Next, in response to the switching signal St from the arithmetic processing section 15, the switch S1 is activated by the pulse signal T! When set to the input side, the switch S3 is in the off state, and the switch S2 is in the on or off state in accordance with the pulse signal output from the arithmetic processing section 13. As a result, the output of operational amplifier A1 changes, the state of transistor Q1 changes, and communication terminal 16.1 changes.
7 to cause a voltage change. This voltage change is applied as a digital signal between the terminals 28 and 29 of the communication device IO via the line 6゜7, and is sent to the CPU of the Tsushin 5'tIO.
21 is detected via the transmitting/receiving circuit 24.

As a result, digital communication is performed from the communication processing unit 15 to the communication device 10. .

On the other hand, Tsushin'? The CPU 21 of ilO is the transmitting/receiving circuit 24
By turning on/off the switch 25 via
When the current from the current source 26 between the terminals 28 and 29 is changed in a pulsed manner, a voltage change occurs between the terminals 16 and 17 of the communication processing unit 15, and the DC component is removed by the capacitor C2 and the one side input of the operational amplifier A2 is generated. Added to the terminal. In response to this, the output of the operational amplifier A2 changes and is input to the arithmetic processing i13 as the received signal RX. Thus, the receiving operation of the positioner 1 is performed.

As described above, the positioner 1 of the embodiment includes one communication device 10
Bidirectional communication can be performed by using , and the digital signal during communication is sent superimposed on the analog signal. Furthermore, when no communication is being performed, there is no power consumption in the communication processing section 15, so that it can function as a positioner in the same way as in the past.

Although the illustrated embodiment has been described above, the present invention is not limited thereto, and any circuits may be used as the constituent elements as long as they have similar functions.

[Effects of the Invention] Since the positioner of the present invention is configured as described above,
By using a communication device connected between a communication terminal and an external power source, power supply for communication and bidirectional communication can be made possible with a minimum number of lines, and remote monitoring and adjustment from the controller side can be realized. Can be done. Furthermore, since there is no power consumption in the communication processing section when not communicating, the effect is that the power consumption is only required as a normal positioner.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a diagram showing the circuit configuration of the input signal detection section of the embodiment, and FIG. 3 is a diagram showing the configuration of a communication device connected to the positioner of the embodiment. 1-111 positioner, 2-111 controller, 3-111 regulating valve, 4-7--transmission line. 8-111 power supply, 9-111 line resistance, 10--1 communication device, 11--one-person power signal detection unit, 12--one lift detection unit, 13--1 communication processing unit . 14----1 electro-pneumatic conversion unit, 15----1 communication processing unit, 16.17----communication terminal, 18----A/D converter, 21----CPU, 22- --- Keyboard, 23 --- Display, 24 --- Transmitting and receiving circuit. 25---Switch, 26---Current source, 27---Filter, 28.29---One terminal. Patent applicant Yamatake Honeywell Co., Ltd. Representative Patent attorney Shindo Hori Patent attorney Kazuko Hori

Claims (1)

[Scope of Claims] An input signal detection unit that inputs a control signal from a controller; a valve lift detection unit that detects a valve lift of a control valve; an arithmetic processing section that performs predetermined arithmetic processing on the control valve and outputs a signal for controlling the drive section of the control valve; an empty conversion section; and a communication processing section that performs a predetermined communication operation according to a signal output from the arithmetic processing section, the communication processing section having a communication terminal for connecting an externally provided communication device; A positioner with a communication function, characterized in that it performs transmission or reception operations based on voltage changes between communication terminals.