JPS5953742B2 - Signal transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a signal transmission method in which transmission and reception are mutually switched between a plurality of communication units to transmit signals, and in particular, the present invention relates to a signal transmission system that transmits signals by mutually switching transmission and reception between a plurality of communication units. By applying a digital signal synchronized with the frequency of the power supply and with one bit per half cycle to the transmitting switching element of the transmitting unit, the signal is received by the receiving element of the receiving unit. The present invention relates to a signal transmission method for transmitting information by identifying the presence or absence of the signal.

Conventionally, the pulse transformer coupling method, line driver/receiver method, and optical coupling method have been adopted for transmitting digital pulses over relatively short distances, such as within factory premises or buildings. Each method has its own problems.

That is, in the pulse transformer coupling method, since the transformer does not transmit a DC component, information must be transmitted by converting DC pulses into AC.

For this reason, complicated equipment such as a modulator and a demodulator is required, which increases the price and has the disadvantage that maintenance is time-consuming. In the line driver/receiver method, in principle, the transmission and reception directions are always fixed, and mutual transmission and reception is not possible. Therefore, if mutual transmission and reception is attempted, the device becomes complicated.

In addition, the optical coupling method is often used for signal transmission between computers and peripheral devices, but because the driver circuit has unbalanced output, it is susceptible to common mode noise and has the disadvantage of causing malfunctions. There is.

Furthermore, in common with the above three methods, in order to synchronize the timing of signals between transmitting and receiving units, a separate synchronization signal line is provided in addition to the data transmission signal line, or a highly accurate synchronization oscillator or complex This has the disadvantage that a circuit is required and the device is expensive.

Therefore, the present invention aims to provide a signal transmission method that completely eliminates the defects of the above-mentioned methods.
The present invention will be described below in detail with respect to an embodiment in which there are two units as shown in the block circuit diagram of FIG. 1, the detailed circuit diagram of FIG. 2, and the timing chart of FIG. 8. ] is a commercial power supply, 2 is a transformer, 3 and 4 are units that mutually function as a transmitting unit and a receiving unit and transmit and receive information signals, and 5 is a signal transmission path. The units 3 and 4 each include communication processing firmware 31 and 4 for processing communication therein, and a communication timing generation circuit 32 connected to the communication processing firmware 31 and 41 and supplying input thereto, respectively.
42 and receiving circuits 33, 43, transmitting gate control circuits 35, 45 that receive the outputs thereof, zero cross detection circuits 34, 44 connected to the transmitting gate control circuits 35, 45 and supplying their inputs, and the receiving circuits 35, 43, A receiving resistor 36 as a receiving element which becomes an input to each of the circuits 33 and 43,
46, and transmission triaxes 37, 47 as transmission switching elements for transmitting the outputs of the transmission gate control circuits 35, 45, respectively. It is connected to the primary side of the transformer 2 by a line 6, and also connected to the receiving resistor 36 of the unit 3 and the transmitting triac 3.
7, the transmitting triax 47 and the receiving resistor 46 of the unit 4 are connected in series in this order with the gate sides of the transmitting triacs 37 and 47 facing each other to form the signal transmission path 5, and the signal transmission The line 5 is connected to the secondary side of the transformer 2, and the windings on the primary side and the secondary side of the transformer 2 are connected and grounded at one end of each.

FIG. 2 is a detailed circuit diagram of FIG. 1, showing the details of each circuit except for the communication processing firmware, and each circuit is shown surrounded by a two-dot chain line.

Here, ``39'' is a photocoupler, and 11 is a DC power supply circuit. Next, the operation of this system will be explained in detail with reference to FIG.

First, the transmitting unit 3 receives the sine waveform shown in A from the commercial power supply 1, and the communication timer generation circuit 32 creates a timing pulse lo that is tuned to the frequency of the commercial power supply 1, and this timing pulse lo is used for communication processing. It is sent to firmware 31.

Therefore, in the communication processing firmware 31, a DC pulse signal to be transmitted that switches between ON and OFF in synchronization with this timing pulse, for example, an air conditioner ON "゜101
A gate control circuit 35 transmits a signal 2 for transmitting data of r.
send to On the other hand, from the zero cross detection circuit 34, the commercial power supply 1
A DC pulse signal that is tuned to the frequency of
゜DC pulse signal whose phase is delayed) is sent to the gate control circuit 3.
5 and applies a gate pulse signal H, which is an AND signal of signal C and signal 2, to the gate of the transmitting triac 37. At this time, the normally open contact 38 of the transmitting side unit 3 is kept open, and the normally open contact 48 of the receiving side unit 4 is kept closed. Now, as mentioned above, when a pulse ho is applied to the gate of the transmitting triax 37 of the transmitting unit 3, a half-wave signal current flows in the signal transmission path 5 in synchronization with this pulse ho and corresponding to the pulse ho. This is unit 4 on the receiving side.
The signal flows through the receiving resistor 46, is waveform-shaped in the receiving circuit 43, and is sent to the communication processing firmware 41, which transmits the information that the air conditioner is ON from the transmitting unit 3 to the receiving unit 4. It means that it was done.

Conversely, when transmitting information from unit 4 to unit 3, the above operations can be replaced, so details will be omitted.

As mentioned above, one of both units 3 and 4 is always in the transmitting state,
The other one enters the receiving state and the states are alternately switched, thereby enabling two-way communication. Further, in the embodiment described above, a receiving resistor is used as the receiving element, but substantially the same effect can be obtained even if an impedance is used instead of the resistor.

As mentioned above, this method is much cheaper than conventional signal transmission methods.

In other words, since this method uses the frequency of the commercial power supply for synchronization, there is no need for a signal line for tuning in addition to the signal transmission line for exchanging information, and for signal transmission, half of the sine wave of the commercial power supply is used. Since a cycle is used for 1-bit signal transmission,
Since a highly accurate tuning oscillator, bit tuning, character tuning, and other complicated circuits are not required, redundant circuits can be omitted and the cost can be extremely reduced. Furthermore, this method can be applied to a wide range of communications such as low-speed data terminal device communications, such as control between indoor and outdoor units of air conditioners, facility control in factories, and building management.

This is because factories and buildings have power distribution equipment, and synchronized AC power is supplied over a wide area. Furthermore, this method can reduce the amount of wiring between units. That is, normally two signal transmission lines 5, 5 are used as shown in FIG.
As shown in Figure 5, commercial power supply lines 6, 6 are wired between the units, and the primary and secondary windings of the transformer 2 are connected at one end. In this case, only one signal transmission line 5 needs to be laid, and one line of the power supply line 6 can be shared as a signal transmission line, so that the number of wiring between units can be further reduced.
Furthermore, since normally open contacts are used in parallel in the transmitter triax, the status of the receiver unit can be checked by the transmitter unit.

That is, when in the reception state, the transmission triac is always in a short-circuited state.

On the other hand, on the transmitting side, when a gate pulse for confirming the receiving side is applied to the triator gate, current flows through the receiving resistor of the receiving side unit, but at the same time, current also flows through the receiving resistor of the transmitting side unit. However, if the receiving side is in receiving state,
That is, if the transmit triac is not short-circuited, no current flows through the receive resistors of both units. Therefore, the transmitting unit can confirm whether the receiving unit is in the receiving state. Furthermore, since this method is a method of transmitting signals using current signals, it can have better noise resistance than a method of transmitting signals using voltage signals.

Incidentally, by synchronizing the timing of the gate pulse of the transmission switching element with the zero potential of the sine wave, it is possible to prevent noise generation when the transmission switching element is turned on.

Furthermore, by making the pulse flow, which is the timing for switching information, different in phase by 90 degrees from the timing of the gate trigger, a margin in timing for information communication can be created.

[Brief explanation of drawings]

Fig. 1 is a block circuit diagram of an embodiment of the present invention, Fig. 2 is a detailed circuit diagram of the device shown in Fig. 1, Fig. 3 is a timing chart showing the operation of the device shown in Fig. 1, and Fig. 4 is an implementation of the device shown in Fig. 1. FIG. 5 is a partial circuit diagram of another embodiment. 1...Commercial power supply, 2...Transformer, 3,
4...unit, 5...signal transmission line,
31, 41... Communication processing firmware, 32
, 42... Communication timing generation circuit, 33, 4
3... Receiving circuit, 34, 44... Zero cross detection circuit, 35, 45... Transmission gate control circuit, 36, 46... Receiving resistor, 37,47・
・・・・・・Transmission trial, 38, 48・・・・・・
Normally open contact.

Claims (1)

[Claims] 1. In each unit of a plurality of units that mutually function as a transmitting unit or a receiving unit, a transmitting switching element and a receiving device are installed, each of which is comprised of a parallel circuit of transmitting triacs 37, 47... and normally open contacts 38, 48... A signal transmission line 5 that connects each transmitting switching element and receiving element is connected to a commercial power source 1 via a transformer 2, and the frequency of the commercial power source 1 is used to synchronize information exchange between multiple units. The half cycle of the sine wave of the commercial power supply 1 is used for 1-bit signal transmission, and the normally open contact of the transmitting unit is opened, and the normally open contact of the receiving unit is closed. A signal transmission method that allows information to be exchanged between multiple units by receiving a digital signal from the switching element of the transmitting unit with the receiving element of the receiving unit.