JPH02219325A - Wire type data collection system - Google Patents

Abstract

PURPOSE:To unnecessitate an insulating transformer of large scale by transmitting a digital signal converted from the output signal of a sensor via a transformer for insulation, and supplying a DC power source to circuits on the middle way via an insulating type transformer. CONSTITUTION:The analog signal of the sensor 16 is converted to a serial digital signal, and is converted to a code format for transmission line at a code conversion circuit 5 via the transformer 4 for insulation, and is sent to a coupling circuit 7. And it is inserted to a signal reproduced and relayed at a relay circuit 7, and is transmitted via a signal line 15. Meanwhile, a DC voltage between the terminals of a diode 9 on a feed line 8 is converted to an AC voltage at a conversion circuit 11, and is converted again to the DC voltage at a conversion circuit 13 via the transformer 12 for insulation, and is fed to the circuits between the sensor 16 and the transformer 4. In such a way, the transformer for insulation can be miniaturized even when the output signal of the sensor includes a low frequency component in the neighborhood of DC, and it can be applied even when a sensor signal includes a DC component.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a wired data collection system, and in particular to wired data that is continuously transmitted and collected through a transmission line while being multiplexed with measurement data obtained at multiple points. Concerning collection systems.

[Conventional technology]

In the conventional wired data collection system of this type, as shown in FIG.
The measurement data is multiplexed at the receiving end station device 21 by continuous connection via a transmission path having a signal line 15 and a power supply line 8.
We are collecting measurement takes. When there are many measurement points or when the total length of the transmission line is long, the ground potential of the feeder line 8 increases, so normally the measurement sensor is 1 and the transmission relay circuit 17, a capacitor C is provided, or an insulating transformer is provided.

[Problem to be solved by the invention]

In the conventional wired data acquisition system described above, the output signal of the sensor 16 includes a fairly low frequency component, and if it is necessary to minimize the insertion loss to this low frequency component, the capacitor C is set to have a large capacity. or it is necessary to increase the inductance of one transformer.
In either case, there is a drawback that the transmitting relay device 20 must be increased in size. Further, when it is necessary to ground one end of the pair of output terminals of the sensor 16, there arises a drawback that the capacitor C and the transformer are increased in size due to the high withstand voltage.

Another drawback is that sensors whose output signal includes a DC component cannot be used.

[Means to solve the problem]

In the wired data collection system of the present invention, an analog electrical signal emitted by a measurement sensor is sent to each transmitting relay device that is continuously connected through a - line transmission path and guided to a receiving end station device, and is converted into a digital signal in DC balanced code format. a signal converting means for converting the digital signal into a signal; and an insulated first converter for AC coupling the digital signal.
a transmitting circuit having a transformer; a coupling circuit that time-division multiplexes a digital signal provided from the transmitting circuit onto a digital signal arriving from the transmitting relay device in the preceding stage via the transmission path and transmitting the digital signal to a subsequent stage; A power supply circuit is provided that converts the DC power obtained from the transmission line to AC, passes through an insulated second transformer, converts it to DC, and supplies power to a circuit between the sensor and the first transformer. .

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. This figure shows an example of the configuration of a line used in the transmission relay device 20 in FIG.
An analog-to-serial conversion circuit (ADC) for converting the output analog signal into a digital signal, 2 a parallel-to-serial conversion circuit for converting a digital parallel signal into a serial signal, and 3 a unipolar converter circuit for converting a digital unipolar signal into a bipolar signal. Bipolar conversion circuit (UBC), 5 is a code conversion circuit for converting the bipolar signal into a code format for the transmission line (signal line 15), 4 is an isolated type for AC coupling the output signal of UBC 3 to the code conversion circuit 5 6 is a relay circuit that regenerates and relays the PCM signal sent from the previous stage device, and 7 is a coupling circuit that inserts the output signal of the code conversion circuit 5 into the time slot assigned to the own device in the PCM signal. , 8 is a power supply line for supplying current to the circuit in the transmission relay device 20, 9 and 10 are constant voltage diodes, 11
is a DC/AC conversion circuit for converting DC power into AC, 1
2 is an insulated transformer for AC coupling, 13 is an AC/DC conversion circuit for converting AC to DC, 14 is a constant voltage circuit for making the DC power constant voltage, and 15 is a signal line for PCM signal transmission. are shown respectively.

In this embodiment, the analog signal of the measurement data sent by the sensor 16 is sent to the ADC 1, the parallel-to-serial conversion circuit 2, and the UCB.
3 and is converted into a bipolar serial digital signal, passed through an insulating transformer 4 and a code conversion circuit 5, converted into a code format for a transmission line, and sent to a coupling circuit 7. The coupling circuit 7 is a PC that has been regenerated and relayed by the relay circuit 6.
After performing synchronization detection of the M signal and inserting the output signal of the code conversion circuit 5 into the time slot assigned to the own device, the signal is continuously transmitted to the subsequent device through the signal line 15.

The circuit (AD
Power is supplied to the CI, parallel-to-serial conversion circuit 2, and UBC 3) from a power supply circuit with an insulating transformer 12 interposed therebetween. That is, the DC voltage between the terminals of a constant voltage diode 9 connected in the middle of the power supply line 8 is converted into AC by the DC/AC conversion circuit 11, and this is input to the DC/AC conversion circuit 13 via the transformer 12. DC conversion, ADC1,
It is used as a driving power source for the parallel-to-serial conversion circuit 2 and the UBC 3.

On the other hand, the DC voltage between the two terminals of the constant voltage diode 10 is stabilized by the constant voltage circuit 14 to obtain driving power for the code conversion circuit 5, the relay circuit 6, and the coupling circuit 7.

In this embodiment, instead of installing an isolation transformer immediately after the sensor 16 as in the conventional system, the output signal of the sensor 16 is converted into a digital signal and converted into a balanced code to eliminate the DC component. Since the bit rate of the digital signal is sufficiently higher than the low frequency component of the output signal of the sensor 16, there is no need to increase the size of the isolation transformer as in the conventional case. Additionally, sensors whose output signal includes a DC component can also be used.

〔Effect of the invention〕

As explained above, according to the present invention, an isolation transformer can be realized in a small size even when the output signal of a measurement sensor includes a low frequency component near DC, and furthermore, it can be applied even when the sensor signal includes a DC component. There is an effect that can be achieved.

It is a lock diagram.

1...Analog-to-digital conversion circuit (ADC),
2... Parallel-serial conversion circuit, 3... Unipolar-bipolar conversion circuit (UBC), 4, 12.19... Transformer, 5... Code conversion circuit, 6... Relay circuit, 7...
・Coupling circuit, 8... Connection wire, 9, 10... Constant voltage diode, 11... DC/AC conversion circuit, 13... AC/DC conversion circuit, 14... Constant voltage circuit, 15... Signal line, 1
6... Sensor, 17... Transmission relay circuit, 20... Transmission relay device, 22... Receiving terminal device, C... Capacitor.

Claims (1)

[Claims] A signal conversion means for converting an analog electrical signal emitted by a measurement sensor into a digital signal in a DC balanced code format, and a signal converting means for converting the analog electrical signal emitted by the measurement sensor into a digital signal in the DC balanced code format, and the digital signal are connected to each transmission relay device continuously connected through a single transmission line and guided to the receiving end station device. a transmitting circuit having an isolated first transformer for AC coupling the transmitting circuit; and a transmitting circuit that time-division multiplexes a digital signal given from the transmitting circuit with a digital signal arriving from the transmitting relay device at the previous stage via the transmission path. a coupling circuit that sends out to the subsequent stage, and an insulated second circuit that converts the DC power obtained from the transmission line to AC.
A wired data collection system, comprising: a power supply circuit that converts the current into direct current after passing through a transformer, and supplies power to a circuit between the sensor and the first transformer.