JPS59136806A - Output device of variable voltage - Google Patents

Abstract

PURPOSE:To obtain easily a variable voltage output device of high accuracy that can set optionally a range of output voltage by combining a variable current output device and a resistance to generate the variable voltage. CONSTITUTION:A digital mimic voltage signal is delivered from a CPU8 incorporated into a test device which confirms the working of a process controller and received by a current output device 15. A current/voltage converting resistance 16 is connected in parallel to the output of the device 15. The device 15 converts the mimic voltage signal into a variable current in response to the level of said mimic voltage signal and delivers it. The CPU8 controls optionally the value of the mimic voltage signal to obtain an optional variable voltage output signal between terminals (c) and (d).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is particularly useful for variable voltage output devices used in trial equipment α for checking the health of process control devices.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The functions and operations of a variable voltage output device conventionally applied to this type of process control device will be described with reference to FIGS. 1 to 3. In FIG. 1, 1 is a process control device, 2 is a process control device;
3 is a test device for confirming the soundness of the process control device 1; 3 is a process signal generator such as a transmitter that is installed at the site and converts process state quantities such as temperature, flow rate, pressure, and water level into electrical signals; 4; , 5 is an amplifier and lead-lag calculator built into the process control device, 6.7
is a relay for interfacing with the test device 2, and is driven by the digital output of the test device, which is not shown in the figure. Further, 8 indicates a central processing unit (hereinafter referred to as CPU) of the test apparatus 2, and 9.10 indicates a voltage output device and a voltage input device, respectively. 20 is an actuator arranged as an operating end. Also a, b, c, d, e, f
is a connection terminal.

Next, the operation will be explained. Normally, the process control device 1 performs calculations based on actual process signals from the process signal generator 3, and outputs required output operation signals to the actuator 20 or the logic controller 20. In this way, when actually operating the process control device 1, the relay 6.
7 is de-energized.

However, in order to check the health of the process control device, static and dynamic characteristic tests of the computing unit are performed. During testing, the relay 6 is energized, the actual process signal from the process signal generator 3 is cut off, and the simulated signal SI from the voltage output device 9 of the test device 2 is sent to the arithmetic unit 4 of the process control device 1.
Enter.

Although current output types are commonly used as process signal generators, since the subject of the invention is a voltage output type, in the description of this embodiment, the voltage output type process signal generator 3 is used.
A description will be given of a type of process control device 1 that operates in the following manner. The output signals of the arithmetic units 4 and 5 are taken into the voltage input device 10 of the test device 2 through the contacts of the relay 7, converted into digital signals via the voltage input device 10, and sent to the CPU 8 by a predetermined value. Compare it with the specified value and judge whether it is good or bad. In this way, the test equipment shown in Fig. 1 mainly uses the amplifier 4.
, a check of the overall characteristics of the lead-lag calculator 5 is performed.

In the test device of FIG. 1, the output voltage range of the process signal generator 3 is included in the output range of the voltage output device 9 of the test device 2, but the input voltage range of the process control device 10 is It may be larger than the output voltage range of the voltage output device 9 for generating voltage signals. For example, while the input voltage range of the process control device 10 is O~.13V,
The output voltage range of the voltage output device 9 for voltage signal generation is 11
This is the case of 0V-10V.

In this way, when the output range of the voltage output device 9 built into the test apparatus is insufficient, the voltage output range can be expanded as shown in FIG. 2 or 3.

In FIG. 2, '+i and i2 are both voltage output devices, and their respective output terminals are connected in series to expand the voltage output range.

Further, in FIG. 3, 13 is a battery, and by further inserting a bias voltage into the output voltage of the voltage output device 9, the voltage output range is expanded.

Conventionally, when it was necessary to expand the voltage output range using such a variable voltage output device, the configuration described above required two voltage output devices, making it difficult to maintain battery terminal voltage accuracy. There were drawbacks such as difficulty in Also second
The method shown in the figure, in which voltage output devices for voltage generation are connected in series, requires that the output voltage output device be isolated from other circuits, but in reality it is highly accurate. Obtaining a small variable voltage output device has been a problem.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and by using a current output device and converting the output current of this current output device into a high precision voltage using a high precision resistor. The object of the present invention is to provide a variable voltage output device that can generate any voltage.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A variable voltage output device according to an embodiment of the present invention will be described below with reference to the drawings. In FIG. 4, 8 is a built-in CPU in the test apparatus 2, 15 is a current output device, and 16 is a current/voltage conversion resistor.

Assuming that the current output range of the current output device 15 as a current generator is 0 to 20 mA, and the voltage output range required as an input signal to the process control device 10 is θ to 13 V, the resistor 1
The value of 6 is -"""-1 arithmetic 20 X 1 o-3iA
According to the output, it is sufficient to use 650 al.

A high-precision resistor is used as the resistor 16 depending on the accuracy of the voltage output required. Further, when the input impedance of the arithmetic circuit of the device under test 2, that is, the amplifier 4 in FIG.

The voltage range that can be generated is limited by the power supply voltage built into the current generator in the current output device 15, but is practically sufficient when applied to the test device 2 of the process control device 1.

Note that in the above embodiment, only the case where a single resistor 16 is arranged in parallel at the output end of the current output device 15 has been disclosed;
It is clear that the resistor 16 may be a 414-type resistor that switches a plurality of resistors, and that the resistor 16 can also be configured as a continuously variable high-precision variable resistor.

As described above, according to the present invention, a variable current output device and a resistor are combined to generate a variable voltage.
This has the effect of easily obtaining a highly accurate variable voltage output device in which the output voltage range can be arbitrarily set.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an analog process control device and test equipment, Figs. 2 and 3 are block diagrams showing a voltage output device using conventional voltage range expansion means, and Fig. 4 is an embodiment of the present invention. 1 is a block diagram illustrating a variable voltage output device according to an example; FIG. 1... Process control device, 2... Test device, 3...
- Process signal generator, 4... Amplifier, 5... Lead/lag calculator, 6. T- Relay, 8... Central processing unit or CPU, 9, 11.12... Voltage output device, 10... Voltage input device, 15... Current output device, 16... Resistor, 20...actuator or logic device. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Makoto Kuzuno (and 1 other person) 587 4 Month 1, Showa 1” Commissioner of the Japan Patent Office 1, Indication of case Patent Application No. 12493/1989 2,
Name of the invention: Variable voltage output device 3, Representative: Hitoshi Katayama Department 4, Agent 1.5B, 'ni/rl, gu 5, Drawing subject to amendment 6, Contents of amendment (1) As attached. Correct Figure 1. (2) Amend Figure 2 as shown in the attached sheet. 7. List of attached documents + 11 One document stating the amended Figure 1 (2) One or more documents stating the amended Figure 2

Claims (1)

[Claims] In a variable voltage output device used in a test device, etc. for checking the operation of a process control device, a digital model a is output from a central processing unit built in the test device.
A resistor is connected between the current output terminals of a variable current output device that receives the t-voltage signal, converts it into a variable current according to the magnitude of the digital simulated voltage signal, and outputs it, and a variable voltage output signal is generated between both terminals of the resistor. A variable voltage output device characterized in that the central processing unit outputs a variable voltage output signal by arbitrarily controlling the value of the digital simulated voltage signal.