JPH0247798B2 - CDTSOCHINODEIJITARUNYURYOKUKAIRO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a digital input circuit in a CDT (Cyclic Digital Telemeter) device that transmits valve opening information, etc. of a water supply system, etc.

(2) Technical background In general, in order to transmit information on the opening of valves scattered throughout a water system to a central processing device, each valve is equipped with an opening gauge. Opening degree information is transmitted by a CDT device connected to. Since such CDT devices, opening degree meters, etc. are installed in remote locations and are almost impossible to operate manually, it is required that opening degree information can be reliably transmitted.

(3) Prior art and problems Figure 1 shows a conventional CDT device. In the same figure
A CDT device is composed of a digital input circuit and a transmission circuit. The digital input circuit inputs the digital input data signal representing the valve opening degree sent from the opening meter and the busy signal to the transmitting circuit in response to a request from the transmitting circuit, and the transmitting circuit transmits these signals to the central processing unit. It is to be sent to. The digital input circuit includes a filter 1, a shift register 2, an address matching circuit 3,
It includes a determination circuit 4 and an output control circuit 5.

The operation of the CDT device shown in FIG. 1 will be explained. A digital input data signal and a busy signal constituted by, for example, a parallel BCD code from a position gauge are input to a filter 1, where noise is removed, etc., and the signals are sent to a shift register 2. On the other hand, an address signal corresponding to the position meter is inputted from the transmitting circuit to the address matching circuit 3, and when the address signal matches a predetermined position meter address, a coincidence signal CS is outputted to the determination circuit 4 and the output control circuit. 5 is input. A data set signal is input from the transmitting circuit to the determination circuit 4, and when this data set signal and the coincidence signal CS are both input, the determination circuit 4 inputs the data read signal DR to the shift register 2. Digital input data and a busy signal are set in the shift register 2 through the filter 1 by inputting the data read signal DR. That is, each data is read from the opening degree meter. Each data read into the shift register 2 is transferred to the output control circuit 5 by the coincidence signal CS and the clock signal inputted from the transmission circuit.
By opening the internal gate circuit, the signal is input to the transmitting circuit as a serial signal and sent out to the transmission line. As described above, in the conventional type, the timing for reading the position gauge data into the digital input circuit is determined by the coincidence of the address selection signal and the data set signal from the transmitting circuit. In addition, the busy signal from the opening gauge is treated at the same level as measurement data,
No special processing was performed using the busy signal in the digital input circuit.

However, in the conventional type, as shown in FIG.
If the timing of the busy signal generated by the CDT device and the timing of the data read signal DR of the CDT device coincided, there was a problem that unstable data would be read and transmitted. In particular, when inputting data that changes significantly in a short period of time, such as valve opening, the busy occurrence interval of the opening meter and the data reading interval of the digital input circuit of the CDT device should be consistent, as shown in Figure 2. However, there was an inconvenience in that it often occurred that no data could be collected while the valve was in operation.

(4) Object of the Invention In view of the above-mentioned problems with the conventional type, an object of the present invention is to provide a latch circuit controlled by a busy signal in the digital input circuit of a CDT device before a shift register for reading input data. Based on the concept of setting up The purpose is to ensure that data can be transmitted accurately.

(5) Structure of the Invention According to the present invention, the object is to acquire digital data from a measuring device into a shift register based on a data set signal, and to transmit data from the shift register through a transmitting circuit. In the input circuit, the digital input circuit is provided with a detection circuit for a busy signal from the measuring device and a latch circuit for temporarily storing digital data, and when the detection circuit detects that the busy signal is off, The digital data is taken into the latch circuit, and the data from the latch circuit is transferred to the shift register based on the data set signal.
This is accomplished by providing a digital input circuit for the CDT device.

(6) Embodiments of the invention Examples of the invention will be described below with reference to the drawings.
FIG. 3 shows a digital input circuit of a CDT device according to one embodiment of the present invention. In the circuit shown in FIG. 1, a latch circuit 6 connected between the filter 1 and the shift register 2 and a busy signal detection circuit 7 for controlling the operation of the latch circuit 6 are added to the circuit shown in FIG. ing. The busy signal detection circuit 7 detects the busy signal from the travel gauge and controls the latch circuit 6. It performs latch control to set the input data from the travel gauge to the latch circuit 6 only when the busy signal is off. Generate signal LS.
With this configuration, it is possible to prevent input data from being read into the shift register during the busy period that is the data update period of the opening gauge. That is, when the travel gauge busy signal is off, the current input data is taken into the latch circuit 6, and the taken data is input as is from the latch circuit 6 to the shift register, and when the busy signal is on, the latch circuit has already been input. The input data of one cycle before, which is set to 6, is input to the shift register 2.

Therefore, as shown in FIG. 4, for example, even if the timing and period of the data read signal DR of the shift register 2 and the busy signal from the position gauge match, unstable data may be sent from the CDT device. do not have.

(7) Effects of the Invention Therefore, according to the present invention, regardless of the timing relationship between the timing of the travel gauge busy signal and the data set signal etc. from the transmission circuit,
The CDT device can accurately transmit position gauge data without transmitting unstable data.

[Brief explanation of drawings]

FIG. 1 is a schematic block circuit diagram showing the configuration of a conventional CDT device, FIG. 2 is a waveform diagram for explaining the operation of the device in FIG. 1, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a schematic block circuit diagram showing the configuration of the CDT device according to the example, and FIG. 4 is a waveform diagram for explaining the operation of the device of FIG. 3. 1...Filter, 2...Shift register, 3...
... Address matching circuit, 4... Judgment circuit, 5... Output control circuit, 6... Latch circuit, 7... Busy signal detection circuit.

Claims (1)

[Claims] 1 Load the digital data from the measuring device into the shift register based on the data set signal,
In a digital input circuit of a CDT device that sends data of the shift register via a transmission circuit,
The digital input circuit is provided with a detection circuit for a busy signal from the measuring device and a latch circuit for temporarily storing digital data, and only when the detection circuit detects that the busy signal is off, the digital A digital input circuit for a CDT device, characterized in that data is taken into the latch circuit, and data from the latch circuit is transferred to the shift register based on the data set signal.