JPH04816A - Signal converter - Google Patents

Abstract

PURPOSE:To simplify the signal converter and to improve economicity by extracting only a signal for the reception side itself among digital signals to be serially transmitted from plural sensors, which enable digital transmission, and outputting the extracted signal after converting it to an analog signal. CONSTITUTION:Sensors 11-14 generate the signals of temperature, static pressure, differential pressure and fow rate or the like, for example. These signals are supplied to a converter 2, successively processed, transmitted through transmission lines to a monitoring device side and commonly inputted to signal converters 31-34. When there are the signals for the signal converters 31-34 themselves among the signals to be transmitted, the converters detect those signals, convert them to the direct currents of 4-20mA and output them to the monitoring device 4. Therefore, the signals generated in the sensors 11-14 are successively switched and transmitted to the signal converters 31-34. Then, when each signal inputted is to be used exclusively for respective signal converters, those signals are outputted as the direct currents of 4-20mA from an analog outputs Ao.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a signal conversion device used in a process control device or the like using a sensor capable of digital transmission.

[Conventional technology]

Conventionally, process control devices send information controlled by the control device to the site, and process values are controlled using the signals. Then, the control result is modulated by a transmitter,
The information is transmitted to a monitoring device provided together with the control device to monitor whether or not desired control is being performed.

[Problem to be solved by the invention]

However, with such conventional devices, one type of signal can be sent with one sensor, so if multiple pieces of information are to be transmitted, sensors for each type of woodcutter are required, and the same number of sensors is required. signal lines were required. However, if the distance between the sensor and the monitoring device is short, there will be no problem, but since the distance Fi is generally about 50 to 500 m, it is extremely uneconomical to provide as many transmission lines as the number of information.

[Means to solve the problem]

In order to solve such problems, the present invention includes a plurality of sensors capable of digital transmission, a first switching means that sequentially switches the output signals of the sensors and outputs them to the track, and a sensor whose number is equal to the number of sensors. It is equipped with a signal converter to which signals received via a line are commonly input, convert only the signal for itself into an analog signal, and output the analog signal from an analog signal terminal.

[Effect]

Since digital signals are transmitted serially via transmission lines, the receiving side extracts only its own signals, converts them to analog signals, and outputs them.

〔Example〕

The figure is a block diagram showing one embodiment of the present invention. In the figure, sensors 11 to 14 are sensors capable of transmitting digital signals, such as signals of temperature, static pressure, differential pressure, flow rate, etc. This signal is supplied to the converter 2, processed in order, transmitted to the monitoring device side via the transmission line, and commonly input to the signal converters 3, -34. If there is a signal for itself among the signals sent, the signal converters 31 to 34 detect that signal and convert it from 4 to 20 m.
The current is converted into a DC current of A and output to a monitoring device.

Therefore, the signals generated in the sensors +j11 to 14 are sequentially switched and transmitted to the signal converters 31-43. And each signal converter @ has an analog output of 4 to 20 mA @ when the input signal is its own signal.
Output as current.

In addition, in this application, since the signal from the sensor is in digital format, it was possible to switch the signal in this way and send the signal over two signal lines, but if this is an analog signal, it is possible to send the signal via a transmission line. Since the signals are transmitted in parallel, multiple transmission lines are required, and with analog, it is not possible to distinguish which sensor corresponds to the signal being output at a certain point in time. It cannot be transmitted using real signal lines.

〔Effect of the invention〕

As explained above, the present invention includes a plurality of sensors that can transmit digital signals, a switching means that sequentially switches the output signals of the sensors and outputs them to the line, and a signal that is equal in number to the number of sensors and that is received via the line. It consists of a signal converter that inputs common signals and converts only its own signal into an analog signal and outputs it from the analog signal terminal, so even if there are multiple sensors, only one transmission line is required. Also, since there is only one converter as an output device, it has the effect of being economical.

[Brief explanation of drawings]

The figure is a block diagram showing one embodiment of the present invention. 1, ~14... @φ sensor, 2... converter, 31
~34...φ signal converter, 4...Monitoring device.

Claims (1)

[Scope of Claims] A plurality of sensors capable of digital transmission; a switching means for sequentially switching the output signals of the sensors and outputting them to the line; and a signal equal in number to the number of sensors and received via the line in common. A signal converter that converts only the signals input to the terminal into analog signals and outputs them from the analog signal terminal.