JPS6231396B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for adjusting the zero point and span point of an analog output device that selects a data signal at a desired point from data signals at a large number of measurement points and outputs it to an analog recorder or the like. It is.

For example, in order to reduce wiring costs, data signals from a large number of measurement locations are collected in one location using a two-wire transmission line, and data from a desired location is selected and outputted to a recorder, etc., for recording location selection as an analog output device. The device has been put into practical use. However, in the case of such a device, since the data is digital signal data from a two-wire transmission line, there is a problem in that it is difficult to adjust the zero point and span point of the analog output section.

The purpose of this invention was to solve the above-mentioned problems.The purpose of this invention was to provide an analog output device in which a changeover switch is provided in the device itself, and zero point and span point signals are generated by changing the changeover switch. An object of the present invention is to provide a method for adjusting the zero point and span point of a device.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a device for exchanging data over a two-wire transmission line.
1 is the main station located in the center, 21, 22...2m are multi-point scanners each having n measurement points, 3
is a recording location selection device as an analog output device to which multiple analog recorders 4 are connected, and l is a two-wire transmission connecting these main station 1, multi-location scanners 21, 22...2m, and recording location selection device 3. It's a line.
Each multi-point scanner 21, 22...2m is n
The measurement data of the locations is scanned, taken in, A/D converted, and then placed on standby.
2...In response to the polling signal to 2m, the multi-location scanner number, location number, and original data are sent to the transmission line 1 as a serial pulse train signal. Main station 1
receives these data, and sends out the location number corresponding to this data, scaled processed data, etc. again to the transmission line l as a serial pulse train signal. These series of operations are constantly repeated, and the data at all measurement locations are updated at regular intervals. The recording location selection device 3 receives, selects, and outputs the data flowing on the transmission line 1.

FIG. 2 is a perspective view showing an embodiment of the recording location selection device as an analog output device according to the present invention. This recording location selection device consists of a box 5 in the shape of a substantially rectangular parallelepiped, and the front portion 5a of the box 5 has a border 5b for embedding in a panel on all four sides. At the upper part of the front part 5a, there is a display 6 for displaying an output location and a measurement location corresponding to the output location, and a setting switch 7 for setting the correspondence between the output location and the measurement location by referring to the display on the display 6. , and a door 8 that can be opened and closed vertically is provided at the bottom of the front part 5a, and a memo card 9 etc. in which the correspondence between the output points and the measurement points is written is stored in the pocket part of the front part of this door 8. In addition, the recess in which the door 8 is housed includes a changeover switch 10 for adjusting the zero point and span point of the output, and a trimmer 11 for adjusting the number of output points.
(In this example, 12 trimmers for span adjustment and one trimmer for zero point adjustment) are provided.

In other words, by pressing the leftmost switch of the setting switch 7, the output location will be displayed on the display 6 above it, and by pressing the center switch, the number of the multi-point scanner and the location number within the multi-point scanner will be displayed. Since it is displayed on the display 6, the output location and the corresponding measurement location are selected with reference to this display, and the measurement data signal of which measurement location is to be outputted from which output location is set. This setting can be made completely arbitrarily, and after displaying the desired setting contents on the display 6, one setting is completed by pressing the rightmost switch of the setting switch, and the settings for the number of output points are completed. Repeat. Also, when the lower selector switch 10 is positioned upward, span point signals for 12 points are generated, and while checking the instructions from the recorder etc. from the output terminal on the back of the box, adjust the span points for the required number of points using the trimmer 11. By positioning the changeover switch 10 downward, the zero point is adjusted by the zero point adjusting trimmer 11a. When the changeover switch 10 is placed in the central RUN position, it becomes operational, and the recording location selection device 3
Outputs the data of the desired measurement point as an analog quantity according to the settings set by the setting switch 7 from among the data signals for all the measurement points flowing through the transmission line l connected to the back of the device. Continuously output from the terminal and record the instructions using an analog recorder, etc.

FIG. 3 is a configuration diagram showing an embodiment of a recording location selection device as an analog output device according to the present invention. In the figure, 12 is a receiving circuit that receives and demodulates a serial pulse signal flowing through transmission line 1 and converts it into a parallel digital signal, etc., 13 is a central processing unit consisting of a microcomputer, etc., and 14 is
A storage unit 15 includes a read-only memory (ROM) in which programs for controlling the arithmetic processing operations of the central processing unit 13 are stored, a random access memory (RAM) for temporary storage, and a nonvolatile memory 14a; A DA converter that converts the signal into an analog signal, 16 a sample and hold circuit having a plurality of output terminals 17 that sample and hold the output of the DA converter, and 6 a display and 7 a setting switch. , 10 is a changeover switch that switches the zero point signal generation contact Z, the operating contact R, and the span point signal generation contact S using a common contact C;
Reference numeral 18 denotes a scale switch which is provided on a circuit board or the like and which determines a constant for the central processing unit 13 to scale data according to the scale specifications of a device such as a recorder connected to the sample hold circuit 16.

The operation will be explained with reference to FIG. Make the following preparations before driving.

(1) At the time of shipping the device, etc., the constant of the scale switch 18 is determined in advance according to the scale specifications of the externally connected recorder, etc. For example, if it is 0 to 1200℃, set L = 0℃ and H = 1200℃,
If the data value is D, the central processing unit 13 calculates the value from 0 to 100 using the calculation formula (DL/HL) x 100.
Scaling is converted to %, making it compatible with all scale specifications.

(2) When the changeover switch 10 is switched to the zero point signal generation contact Z, the central processing unit 13 switches to the DA converter 1.
5 generates a digital zero point signal, and switches to the span point signal generation contact S, the central processing unit 1
3 generates a span point signal to the DA converter 15, and are located inside the front door 8 of the device shown in FIG. Adjustment can be performed using the zero point adjustment trimmer 11a. Then, by switching to contact R, the normal operating state can be achieved.

(3) The correspondence between the output points and measurement points set by the setting switch 7 with reference to the display 6 is as follows.
This data is stored in the non-volatile memory 14a of the storage unit 14 and transferred to the RAM during setting and when power is turned on.
Normal data processing is performed according to the contents of RAM, and it is handled in the event of a power outage.

That is, after the above preparations are completed, the recording location selection device as an analog output device is put into operation.

Data signals from multiple locations flowing through the 2-wire transmission line l are constantly supplied to the device, are constantly received by the receiving circuit 12, and are sent by the central processing unit 13 to the measurement locations that are preset and stored in the RAM by the setting switch 7. It is determined whether or not the numbers match, only the data with the matching numbers are selected, and arithmetic processing such as the above-mentioned scaling conversion is performed using a constant determined by the scale switch. The data processed by the central processing unit 13 is converted into an analog signal by the DA converter 15 and output from a predetermined output terminal 17 of the sample hold circuit 16. These series of operations are constantly repeated, and the output signal from the output terminal 17 is input to multiple analog recorders and the like, and is used for recording and monitoring at all times.

As described in detail above, the present invention connects data signals from a large number of measurement points to a two-wire transmission line through which they flow as serial pulse train signals, and selects a desired point from the data signals flowing through the two-wire transmission line. After selecting the data signal and converting it from analog to analog, the sample and hold circuit outputs the zero point signal and the span point signal to the analog output device by switching the changeover switch, supplying the zero point signal and the span point signal to the D to A converter,
The zero point and span point of the output signal are adjusted.

Therefore, it is possible to adjust the zero point and span point of the output circuit by generating a zero point signal and a span point signal using a changeover switch provided in the device, so that the input signal is a serial pulse signal on the two-wire transmission line. Even though it is difficult to input the adjustment signal easily, the adjustment can be made extremely easily.
Furthermore, since the reference point signal can be generated within the device, there is no need to prepare a special external standard generator, and adjustments can be made extremely easily on site. Furthermore, since the reference signal is a digital quantity rather than an analog quantity, there is no drift error due to aging or changes over time, and accurate adjustment is possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a device for sending and receiving data on a transmission line according to the present invention, and FIG. 2 is a block diagram showing an embodiment of a recording location selection device as an analog output device according to the present invention. The perspective view shown in FIG. 3 is a block diagram of the same configuration. 3... Recording location selection device as an analog output device, 5... Box, 6... Display, 7... Setting switch,
8... Door, 10... Changeover switch, 11, 11a... Trimmer, 12... Receiving circuit, 13... Central processing unit, 1
4...Storage device, 14a...Nonvolatile memory, 15...D
-A converter, 16...Sample hold circuit, 17
...Output terminal, 18...Scale switch.

Claims (1)

[Claims] 1 Connected to a 2-wire transmission line through which data signals from a large number of measurement locations are flowing as serial pulse train signals, select the data signal from a desired location from the data signals flowing through this 2-wire transmission line, and perform D-A. In the analog output device that outputs from the sample hold circuit after conversion, by switching the changeover switch, the zero point signal and span point signal can be supplied to the DA converter, and the zero point and span point of the output signal can be adjusted. A method for adjusting the zero point and span point of an analog output device, characterized in that: