JPH01147800A - Multipoint input signal converting device - Google Patents

Abstract

PURPOSE:To remove a defective element for a signal line by enabling a multipoint input signal converting device to communicate an optical digital signal with a host apparatus, etc., through an optical fiber cable. CONSTITUTION:The signal quantity of a detector 31 is given to the multipoint input signal converting device 1, and converted into a prescribed electric signal by a detection circuit 11. Digital quantity, i.e., the measured value of respective input point is converted into the optical digital signal by an E/O interface 17, and received by the light receiving element of an optical connector 18, and transmitted to a host apparatus through the optical fiber cable 2. On the contrary, instruction from the host apparatus takes the form of the optical digital signal as well, and is given to the device 1 through the optical fiber 2. Thus, since the device 1 is made capable of transmission and reception by using the optical digital signal by connecting it to the host apparatus, etc., through the optical fiber cable, the defective element for the signal line can be removed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention converts analog input signals supplied from a large number of measurement points into digital signals, converts them into digital signals, and then connects optical fiber cables. The present invention relates to an input signal conversion device capable of receiving commands and data from a higher-level device while transmitting the same to a higher-level device via a high-level device.

[Conventional technology]

At present, no optical fiber type multi-point input signal conversion device is known, and a similar device shown in FIG. 5 is known.

The one shown in the same figure (A) is provided with a conversion device Cv and a control device CT for each of a plurality of detectors (sensors) S,
A conversion device C that converts the measurement signal from each sensor S to the corresponding one.
The signal is converted by V and transmitted to the control equipment CT including the host system via the electric signal line CAt-. Note that SL indicates an input signal line.

On the other hand, the one shown in the same figure (b) is different from the one shown in the same figure (a) in that one control device C'l is provided in common.
Moreover, what is shown in the same figure (c) is one in which the conversion device Cv is also made common to the same figure (b).

The conversion devices used in this work include, for example, a detection circuit, an amplifier circuit, and a range switching circuit, as shown in FIG.

It is composed of an A/D conversion circuit, a processing unit CPU, a signal conversion interface, etc. In addition, as a range switching circuit, for example, a positive phase amplifier (operational amplifier) 4 as shown in FIG.
1.42 and an analog switch 43 are used.

[Problem that the invention seeks to solve]

However, in the configurations shown in Figures 5 (a) and (b),
Although the purpose of measuring many measurement points can be achieved, both of these methods increase the cost of individual wiring and maintenance, making the system itself relatively expensive, and as a result, it is difficult to rationalize the system. Furthermore, since the converting devices are scattered, data density is low and reliability and safety are also poor. Also, the one shown in Figure (C) is more streamlined than those in Figures (A) and (B), but there is an electrical signal line between the converter and the control equipment. Therefore, the farther away the converter and control equipment are, the more induced noise will occur, especially if the electrical signal lines between them are exposed to the outside world.

The drawback is that it is fundamentally vulnerable to lightning noise, door wave interference noise, etc. For this reason, in the system configuration shown in Figure 5 (c), there is a problem with the reliability of transmitting measurement data from the converter to the host device), and there is also a problem with remote adjustment of the converter from the host device, etc. If you try to do this, there is a drawback that failures in the signal path will affect the reliability of adjustment data, setting data, etc.

In order to avoid this drawback, it is conceivable to provide the conversion device with an adjustment function or the like. However, providing the conversion circuit with such an adjustment function, a separate range adjustment function, etc. increases the hardware cost and complicates the circuit. In particular, the circuit system that includes volume adjustment, which has been frequently used in the past, has the drawback of not only increasing the effort and cost of adjustment, but also decreasing efficiency. In addition, in order for the converter to be constructed in a highly safe manner for the purpose of intrinsically safe explosion-proofing, it is required to suppress the electrical energy that can cause an explosion, but conventional devices are not necessarily sufficient in this respect. I can't say it. Furthermore, it would be time-consuming for the adjuster to go to the remote converter every time there is a need for readjustment or range change.
This means that labor savings cannot be achieved.

In particular, in many cases conventionally, the input range is changed by using a circuit as shown in FIG. 7, and changing the gain using a switch or the like using a control signal line LC. but,
In such a circuit, the switching possibilities for changing the range are limited to the number of switching stages of switches provided in the conversion circuit and the number of switching combinations of the gain resistance constant of the amplifier circuit. Setting changes is not always easy. In addition, since it is not always possible to change the range directly from a remote location, if it becomes necessary to change the range due to a change in the process input status, etc. There are problems such as the need to operate switches etc. by some means.

Therefore, the present invention enables a conversion device to communicate optical digital signals with higher-level equipment via an optical fiber cable, thereby making it possible to eliminate obstacles to the signal path and to transmit optical signals from a higher-level device. By making it possible to receive commands (range change commands, data setting commands, etc.) using digital signals, remote range changes can be performed at all points of a multi-point input, eliminating switching limitations. The aim is to make this process flexible and easy.

[Means for solving problems]

Optical fiber cables are used to connect a multi-point input signal converter that is equipped with at least a data processing function and that sees the measurement signal tS from multiple measurement points and converts it into a digital signal, and other equipment including a host processing device. An optical signal transmitting/receiving means is provided for transmitting and receiving information via a Performs range setting or change processing for measured values.

[Effect]

It is possible to connect an optical fiber cable to a multi-point input conversion device, convert the input signal and make it possible to use optical digitization, and also to comply with predetermined transmission regulations (
By making it possible to exchange information with higher-level equipment using optical digital signals in accordance with the protocol), conventional failure factors can be removed, and commands (
(remote range change, remote setting, etc.) In particular, the range of possible range settings can be changed for each point of a multi-point input signal by several recirculation switching settings and Rather than changing the range, the range can be changed arbitrarily and flexibly within the range that can be set, and it is easy to do so.

〔Example〕

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention. Here, the target of multi-point input signals, that is, the measurement target is a temperature physical quantity, and the detector is a thermocouple or a resistance temperature detector. can. In the figure, a detector (senna) 31 is a thermocouple or a resistance temperature detector, and 32 is a conductor or a compensation conductor that is connected to the input terminal (not shown) K of the sensor and converter 1. . Note that the conversion device 1 includes a detection circuit 11. Amplification circuit 12. multiplexer IS,
V/F circuit 14. Processing unit (CPU) 15, optical/electrical (
0/B) Conversion unit 16. (electrical/optical (Elo) converter 17, optical connector 18, etc.).

The signal amount from the sensor 31 is first converted into a constant electrical signal by the detection circuit 11. For example, the thermoelectromotive force from a thermocouple has a voltage value within a certain range (for example, 0 to 100 mV),
In addition, the resistance input of the resistance temperature sensor is applied to a voltage within a certain range (for example, 0 to 100 mV) by a bridge circuit in the detection circuit 11.
is converted to

In the next stage amplifier circuit 12, a larger voltage (
For example, the voltage is amplified to 1 to 4 V). One input channel is selected from the multiple input signals by an analog multiplexer 13. Input selection is performed by commands from the CPU 15, and a series of controls are executed by software built into the CPU. The selected voltage is V
The /F circuit 14 converts the pulse width into a large or small pulse width. That is, the magnitude of the signal detected by the sensor is converted into the magnitude (length or shortness) of the pulse width at this stage. This pulse width is
It is counted by an internal reference timer included in the CPU 15, and is converted into a highly accurate digital quantity. The CPU 15 sequentially performs control related to a series of measurements, such as various correction calculations such as temperature correction accompanying digital quantity conversion. That is, the CPU 15 grasps and stores the measured values for all input points as digital quantities.

Next, the digital quantity that is the measured value of each input point is E
The signal is converted into an optical digital signal by the 10 interface 17 and transmitted to the upper layer. In this case, the E10 interface 17 is mainly composed of an LED (light emitting element), a current limiting resistor, etc. as shown in the figure. The light emitted by the LED is received by the light receiving element of the optical connector 18, and an optical signal is transmitted by the optical fiber cable 2. In the fall, on the other hand, a command from a higher level is given to the converter 1 via the optical fiber 2, also in the form of an optical digital signal.

From the converter's perspective, this means receiving an optical digital signal. The transmission/reception signal form of this optical digital signal shall be determined in advance as a transmission protocol (protocol). The optical digital signal from the host is 0/E.
It is received by the CPU 15 via the interface 16.

As shown in the figure, the O/E interface 16 is mainly composed of a photodiode, a current limiting resistor, etc. Note that both the 0/E and E10 interfaces use photocouplers (
By further insulating the signal path with a filter (not shown), the optical fiber is shielded from noise, and more careful measures are taken to improve reliability.

In this way, information regarding the measurement of input signals at multiple points is sequentially and cyclically transmitted and received as optical digital signals for each point. Note that, as described above, the conversion device according to the present invention includes the detection circuit 11, the amplifier circuit 12. Multiplexer 13. V/F circuit 14. CPU15. It is composed of an O/E interface 16j, an E10 interface 17, and several basic circuit elements, but these elements are all made using only low power elements such as C-MO8ICs and low power type amplifiers. The electrical energy of the converter is suppressed, and the structure is designed to have enough margin to reach the explosive energy. In addition, disturbance factors to the conversion device itself include: ■Noise interference in the input signal path;
There are three main types of obstacles that can be considered: (1) Noise interference from the power supply system, (2) The influence of radiated interference waves on the converter itself, etc. However, by taking the following measures,
This allows the use of optical fiber cables to be fully utilized.

In other words, filtering, bypass, noise penetration, etc. are implemented for the input signal path (■), and surge absorption and high-frequency noise are also implemented for the power supply path (■).

For example, take measures such as absorbing low-frequency noise, and for ■, sufficiently shielding, guard rings, and grounding rings on the converter to block interference from the converter.
Concrete measures are being taken to the fullest.

FIG. 2 is a flowchart for explaining the operation of FIG. 1. That is, it detects the serial input from the host device (see (2)) and checks whether the own conversion device is specified (see (2)). If the result is NO, the process returns to step ■, but if YES, it is determined whether or not it is in the measurement mode (see ■), and if YES, the measurement data up to that point is sent to the host device (see ■), and the input Predetermined operations on signals.

Make corrections (see ■ and ■). If NO in step (2), determine whether or not it is in the range change mode (see (2)). If yes, perform the range change operation (see (2)), and if no, return to step (2).

FIG. 3 is a schematic diagram showing an example of a measurement system using the above conversion device. Reference numeral 1 denotes a multi-point input signal converter), which is connected to a higher level by an optical fiber cable 2.

Reference numeral 3 denotes a bidirectional optical splitter called an optical star coupler, in which the optical signal of one optical fiber cable 4 is branched into optical signals of eight optical fiber cables 2.

The optical fiber cable 4 is connected to the master station 5, which is a host device! [Reru. The master station 5 corresponds to a central control device that centrally manages, monitors, and controls data from lower-order conversion devices. The master station 5 can be connected to higher-level control equipment and computer network systems. In this case, by connecting four optical fiber cables 4 to the master station 5 and coupling each of them to the star coupler 3, a maximum of 32 conversion devices can be connected to one master station 5.

The mask station 5 divides the optical digital signal information into numbers for up to 32 devices so that it can be determined which device the information corresponds to. As a result, if one conversion device converts input signals from a maximum of 16 points, it is possible to centralize measurement target data for a maximum of 512 points, making it possible to increase the data density. The system is much more streamlined and more reliable than conventional systems.

In the following, input range switching will be explained in comparison with the conventional method.

Conventional range switching circuits often use analog switches to switch fixed gains, as shown in Figure 7.
fixed range method). That is, in the circuit of FIG.
For example, when the gain G1 of the operational amplifier 41 is 01=47, the gain G2 of the operational amplifier 42 is determined by the internal switching of the analog switch 43) -t-re, A: 1x, B: 2x, c
: a times, D: 8 times, the total gain G (
GI XG2) is as shown in the following table.

Table <1> Now, let us assume that the process amount is 0 to 100.
It handles a temperature measurement range of 0℃, and the span (SPAN) is 85 m for an input signal of 00 to 100% input to the converter.
V, i.e. 0 to 85 mV, and assuming that selector switch A is closed, the output stage V. Then 3995 (
85mV x 47x) mV S PAN, i.e. O~3
995 mV corresponds to 0-100%.

2〉 In and ~, the state of the process is different from <1>,
If we treat the measurement range of 0 to 125 °C as the temperature of the process state, and it corresponds to an input of 00 to 100%, then if the maximum span of the input signal input to the converter is 10 mV, i.e., 0 to 10 mV, then If the measurement range is the same as in case <1>, the switch is closed, so the output stage V. In this case, the span is 470 mV, so the output is 0 to 1 for an input of 0 to 100% (0 to 125 @).
1.76% (0-47015995)t.

Otherwise, you will not be able to get it. Therefore, even if the process state input is a 100% measurement quantity of 125°, the output of the converter, that is, the measurement data obtained by the host device is 125°C x 117°.
6% = 14.7°C, so the input and output cannot be matched, and less than 1/8 of the signal range that can be handled is used. Therefore, by changing the range with switch D, it is necessary to adjust the range so that the input 0 to 100% is matched to the output 0 to 100%. Due to this, υ, for temperature measurement,
Measurement resolution of 1°C temperature can be improved.

FIG. 8 shows the relationship between input and output when range switching is performed in this manner. In other words, by arbitrarily switching the four fixed ranges for the input, the input 00
The output can be range adjusted from 0 to 100%. It should be noted that the straight lines ``■'' to ``■'' respectively correspond to the switching of the above-mentioned switch AS-D.

However, in the fixed range method as described above, (a) Even if it has a range switching means, depending on the input range, the range may change from 0 to
The output does not necessarily exactly match 0 to 100% for 100% input.

For example, in the above example, even if switch DK is changed, the input is 0.
~100%, the output is 0~94.08% (5760
15995). Unfortunately, the input/output relationship is not consistent, and some parts of the conversion are inadequate.

(b) The range of range switching is restricted and limited.

(c) It is necessary to switch ranges on the converter side depending on the input.

(d) If an attempt is made to solve this problem by using a volume resistance adjustment method or the like for the amplification gain resistance, the consistency of input-output conversion (a) can be satisfied, but the operation becomes complicated.

(e) In the case of multi-point input, the problem of how to adjust the range of each point has not yet been resolved.

(to) Therefore, there is a lack of flexibility in range adjustment.

There are problems such as.

Therefore, in the present invention, the following steps are taken.

That is, range adjustment/setting and range change are performed using the CPU and internal memory in the converter according to a predetermined transmission procedure with the host device. For example, if an input signal equivalent to 0 to 1000°C is input to the sensor and converter, and zero adjustment and span adjustment are performed at each temperature, the input signal equivalent to 0°C and 1000°C is
Each of them is subjected to V/F conversion in a conversion circuit, and finally stored as a digital value at a predetermined memory address within the CPU. That is, a zero point for each point of input.

The digital value of the span input data is
It is stored in a predetermined memory area within. At this time, the span
Since the range is 100%, the value ``1100%'' is stored, and since the zero range is 0%, the value ``0%'' is stored at a predetermined address in the CPU memory in the same manner as above.

Note that this zero range (hereinafter abbreviated as RAGZ).

The value of the span range (hereinafter abbreviated as RAGS) can be set by setting data from the upper level. Also,
When set on the upper side, this value is also stored in the memory on the upper side. Data transmission from the upper level side and data reception at the conversion device side are performed according to a predetermined transmission procedure.

The input/output relationship when the input range is changed is shown in a graph in FIG. 4 (A), and the range setting values are shown in FIG. 4 (B). For example, as in the case of $4 Figure
When changing the range to 00℃ measurement range, change the RA from the upper
GZ=3α0%.

This is done by setting RAGS=50.0% and having the conversion device receive this setting data as an optical digital signal. In other words, on the converter side, the contents of the range stored in advance are updated and 300°C to 800°C is input 00 to 800°C.
It is treated as 100%, and the input for this measurement range is 0 to 1.
It is output to the host device as 00%. The conversion device refers to this updated memory content, performs the next operation, and outputs the result to the host device.

In this way, RAGZ and RAGS data can be transmitted remotely by optical data transmission from the host device.

A range change will be realized.

(1) In the maximum input range, the measurement range is not restricted as compared to the conventional fixed range method, and the range can be changed with flexibility.

(2) Output 00-100% for input 0-100%
corresponds correctly, so consistency between input and output is maintained.

(3) Since it can be adjusted remotely, it is rational and labor-saving.

(4) Since the conversion device incorporates various reliability measures, reliability during remote range setting and changes can be guaranteed by adopting a configuration that allows connection to the optical 7-IPA cable. Ru.

(5) By utilizing the flexible nature of memory, it is easy to change the range for each point of multi-point input, and it is possible to flexibly cope with an increase in the number of input points.

(6) By using memory, it is possible to change the range for all input points at once from the upper level, or for each point individually), making it an extremely flexible conversion device. It can be done.

There are advantages such as

〔Effect of the invention〕

According to the present invention, (1) Since the multi-point input signal conversion device is connected to host equipment etc. via an optical fiber cable and can transmit and receive optical digital signals, obstacles to the signal path are removed. be able to. In particular, in systems where the number of input points increases, reliability of data communication is strongly required, so it is suitable for use in cases where data communication is unstable.

(2) The multi-point input signal converter has the advantage of being able to remotely and flexibly change ranges for all of the multi-point input points using optical digital signals from a host.

(3) Since one multi-point input signal conversion device itself becomes an element that takes reliability into consideration, multi-point input signals can be intensively converted to improve data density, and the data can be further processed at the upper level. There is reliability in centralizing and managing data, and it also has the effect of achieving rationalization associated with centralizing and managing data.

(4) By integrating these individual effects, maintenance and
Easier maintenance, reduced costs, lower cost conversion equipment (higher cost performance), and rationalization of the Rahini system.
This has the effect of saving labor and increasing reliability.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 2 is a 70-day diagram for explaining the operation of FIG. 1, and FIG. 3 is a schematic diagram showing the configuration of the entire measurement system including the present invention. FIG. 4 is an explanatory diagram for explaining range setting and changing operations according to the present invention, FIG. 5 is a block diagram showing a conventional example of a measurement system, and FIG. 6 is a block diagram showing a conventional example of a conversion device.
FIG. 7 is a circuit diagram showing a specific example of the range switching circuit, and FIG. 8 is a graph showing the relationship between input and output when range switching is performed in FIG. 7. Code explanation 1...Multi-point input signal converter, 2, 4...
...Optical fiber cable, 6...Optical Star Cub 5.5 = Master station, 11...
...Detection circuit, 12...Amplification circuit, 13...
...Multiplexer, 14...V/F circuit,
15... Processing unit (CPU), 1゛6...
...0/E interface, 17...E10 interface, 18...optical connector, 31...
...Detector (sensor), 32...Compensation conductor or conductor, 41.42... Positive phase amplifier (operational amplifier), 43... Analog switch. Agent: Akio Namiki, Patent Attorney: Kiyoshi Matsuzaki, Patent Attorney: h.

Claims (1)

[Claims] A multi-point input signal conversion device that is equipped with at least a digital processing function and that receives measurement signals from a plurality of measurement points and converts them into digital signals, wherein An optical signal transmitting/receiving means is provided for transmitting and receiving information via an optical fiber cable between A multi-point input signal conversion device characterized by performing range setting and changing processing for digital measurement values at each measurement point.