JPH01316026A - A/f conversion transmitter - Google Patents

Abstract

PURPOSE:To eliminate the need for any shield wire and to reduce number of transmission lines by converting an analog quantity into a frequency signal according to the timing control and sending the result. CONSTITUTION:With a power supply of a processing unit 4 turned on, a current flows to a line 5 through a resistor 19 to charge a capacitor 15. If the voltage across the capacitor exceeds a Zener voltage (16), a prescribed voltage is applied to an A/F conversion and control circuit 1. Thus, a timing control circuit 11 is operated to count a charge waiting time zone T1. When the time T1 is elapsed, the circuit 11 operates a conversion storage circuit 12 to count an A/F conversion time zone T2. The circuit 12 converts the change of an input analog quantity or the like into a frequency proportional thereto and stores the result temporarily. Since the charging is continued during that time. The operation of the circuit 12 is stopped by a command from the circuit 11 at a signal transmission time band T3 and the transmission control circuit 13 is operated. The circuit 13 converts the data in the circuit 12 into a serial data, a FET 17 in the switching circuit 3 is subject to on/off control based thereupon to send a binary data to the unit 4 via a line.

Description

DETAILED DESCRIPTION OF THE INVENTION A summary processing device of the invention and an A/F conversion device are connected by a power supply and signal transmission line. The A/F conversion device includes an A/F conversion circuit, a constant voltage circuit, a timing control circuit, and a switching circuit for the above-mentioned lines. After the time zone control of the timing control circuit.

First, the constant voltage circuit is charged through the above line.

The A/F conversion circuit operates with this charged power and is supplied through the above line, converting the analog signal into a frequency signal, and the charged power causes the switching circuit to respond to the frequency signal after A/F conversion. By being driven by.

A voltage change corresponding to the frequency signal appears on the line. This voltage change is received as a signal by the processing device.

[Technical Field] The present invention relates to an A/F conversion transmission device, and particularly to a device that converts an analog signal detected or generated far from a processing device into a frequency signal and transmits the frequency signal to the processing device.

[Prior art] If you try to transmit the analog signal as it is from the point where it is detected or generated to a processing device far away, you will have to use shielded wires to prevent noise and wiring capacity, which is expensive. There is a problem with that. Further, an adjustment circuit for them is required, and this adjustment work is necessary.

The above-mentioned problems can be solved by providing an A/F conversion circuit at the point where the analog quantity is detected or generated, converting the analog signal into a corresponding frequency signal, and transmitting the signal to the processing device. However, since power is required to operate the A/F conversion circuit, a battery is provided to supply this operating power, or a power supply line is connected from the processing device in addition to the frequency signal transmission line. Wiring must be done over long distances.

Purpose of the Invention This invention eliminates the need to use shielded wires for noise countermeasures by converting analog quantities into frequency signals and transmitting them, and also allows the signal transmission line and power supply line to be shared. An object of the present invention is to provide an A/F conversion transmission device that can reduce the number of lines.

[Structure and Effects of the Invention] The A/F conversion and transmission device according to the present invention includes a processing device that supplies operating power and receives an A/F conversion signal, and a processing device that is connected to the processing device by a power supply and signal transmission line. A/
It consists of an F conversion device. The A/F conversion device has an A/F conversion circuit that converts an analog signal into a frequency signal, a timing control circuit that controls operating time, charges the current flowing through the line, and generates the operating power of a constant voltage = 3 - as described above. A constant voltage circuit that supplies the A/F conversion circuit and the timing control circuit, and the A/F converter that is connected to the above line.
A switching circuit is provided which is controlled by the output of the /F conversion circuit. Then, the timing control circuit controls the charging time period of the constant voltage circuit, the A/F conversion time period of the A/F conversion circuit, and the signal that is A/F-converted by driving the switching circuit. A signal transmission time period for changing the voltage is defined, and the A/F conversion circuit is controlled to perform the desired operation during this time period.

After the time zone control of the timing control circuit, the constant voltage circuit is first charged through the above line, and the A/F conversion circuit is operated by the charged power and supplied through the above line to convert it into an analog signal or a frequency signal. The converted and charged power causes the switching circuit to
/ ' By being driven in response to the frequency signal after F conversion, a voltage change corresponding to the two-frequency signal appears on the above line. This voltage change is received as a signal by the processing device.

Analog signals generated or detected at a location far away from the processing device are converted at that location into a signal having a frequency corresponding to the analog quantity, and sent to the processing device. Therefore, shielded wires, adjustment circuits, and adjustment work required when transmitting analog signals as they are are no longer necessary, and the system is less susceptible to noise and the like. In addition, since the transmission line for one frequency signal and the line for supplying power to operate the A/F conversion device are shared, the number of lines wired between the processing device and the A/F conversion device can be kept to a minimum. be able to. This is particularly effective when a large number of A/F conversion devices are connected to one processing device.

[Description of Embodiment] In FIG. 3, one processing device 4 is connected to a large number of A/F conversion devices 10 by a power supply/signal transmission line 5.

An example of a specific configuration of the A/F converter 10 and a part of the configuration of the processing device 4 are shown in FIG. 1, and the voltage appearing on the line 5 is shown in FIG. 2, respectively.

Referring to these figures, the A/F conversion device 5.

It is composed of an A/F conversion and control circuit 1, a constant voltage circuit 2, and a switching circuit 3.

The A/F conversion and control circuit 1 includes a timing control circuit 11 for controlling the operating time period. Resistance value.

A conversion storage circuit 12 that converts a voltage value or other detected or generated analog signal into a signal with a frequency corresponding to the analog quantity it represents and temporarily holds it. and - a transmission control circuit 13 for controlling serially sending out the temporally held contents to line 5;

The constant voltage circuit 2 includes a charging capacitor 15 connected between lines 5. Zener to maintain constant operating voltage
It includes a diode 16 and a backflow prevention diode 14. The switching circuit 3 includes a FET 17 connected between the lines 5, and this FET 17 is connected to the transmission control circuit 13.
Controlled on/off by

One of the lines 5 is connected to a power supply via a resistor 19 of the processing device 4, and the other is grounded, for example. resistance 19
The voltage at the connection point between and line 5 is received in the input circuit 18 as a received signal.

First, when the power of the processing device 4 is turned on, a current flows through the line 5 through the resistor 19 and the capacitor 15 is charged. When the terminal voltage of capacitor 15 becomes higher than the Zener voltage of Zener diode 16, a constant voltage is applied to A/F conversion and control circuit 1.

As a result, the timing control circuit 11 starts operating,
The time T1 required for the capacitor 15 of the constant voltage circuit 2 to be sufficiently charged (charging waiting time period) is measured. During this time period T1, the conversion storage circuit 12 and the transmission control circuit 13 stop operating, and the current consumption of the A/F converter 10 as a whole is suppressed to a minimum.

When the charging waiting time T1 ends, the timing control circuit 1
1 outputs an operation start command to the conversion storage circuit 12 and starts counting the primary time (A/F conversion time zone) T2. The conversion storage circuit 12 converts a change in an externally applied or generated analog quantity (for example, a resistance value or a voltage value) or its absolute quantity into a frequency proportional to the change,
-Remember temporally. This frequency is maintained, for example, as a constant time count of input pulses. Even during this time period T2, charging of the capacitor 15 of the constant voltage circuit 2 continues.

At the next time (signal transmission time period) T3.

An operation stop command is sent from the timing control circuit 11 to the conversion storage circuit 12, so this circuit 12 stops its operation, and an operation start command is input to the transmission control circuit 13.

The transmission control circuit 13 converts the parallel data temporarily held in the conversion storage circuit 12 into serial data,
Based on this, a signal for controlling the FET 17 of the switching circuit 3 to be turned on or off is output.

For example, if the data is 1, FET 17 is turned on and the current in line 5 flows through this FET 17.

Therefore, the potential at the connection point between resistor 19 and line 5 is L
level, and an L level signal is input to the input circuit 18. Since the constant voltage circuit 2 is provided with the diode 14, the charge in the capacitor 15 will not be discharged through the FET 17. When the data is 0, the FET 17 is held in an off state, so the input signal of the input circuit 18 is at H level. In this way, binary data is transferred to FET17.
The signal is transmitted to the processing device 4 through the line 5 depending on whether the signal is turned on or off.

During this time period T3, the operating power of the timing control circuit 11 and the transmission control circuit 13 is covered by the charge stored in the capacitor 15 of the constant voltage circuit 2.

When the time period T3 ends, an operation stop command is sent from the timing control circuit 11 to the transmission control circuit 13, and
This circuit 11 starts timing the time period T1. As described above, the operation consisting of two time periods T1 to T3 is repeated.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing the configuration of the A/F converter and a part of the processing device, Fig. 2 is a time chart showing the operation of the A/F converter according to changes in line voltage, and Fig. 3 is a circuit diagram showing the configuration of the A/F converter and a part of the processing device. FIG. 2 is a block diagram showing a state in which a plurality of A/F conversion devices are connected to a processing device. 1...A/F conversion and control circuit. 2... Constant voltage circuit. 3... Switching circuit 5 4... Processing device. 10...A/F conversion device. 11...timing control circuit. 12... Conversion storage circuit. 13...Transmission control circuit. that's all

Claims (1)

[Claims] The above-mentioned A/F conversion device is composed of a processing device that supplies operating power and receives an A/F conversion signal, and an A/F conversion device connected to this processing device by a power supply and signal transmission line. The /F conversion device includes an A/F conversion circuit that converts an analog signal into a frequency signal, a timing control circuit that controls operating time, and a charging current flowing through the above line and supplying operating power of a constant voltage to the above A/F conversion circuit. and a constant voltage circuit that supplies the timing control circuit, and a switching circuit that is connected to the line and controlled by the output of the A/F conversion circuit, and the timing control circuit is configured to control the charging time of the constant voltage circuit, Determine an A/F conversion time period by the A/F conversion circuit and a signal transmission time period in which the voltage of the line is changed based on the A/F converted signal by driving the switching circuit, and
An A/F conversion transmission device that controls an A/F conversion circuit.