JPS61208929A - Two-wire remote control system - Google Patents

Abstract

PURPOSE:To reduce the fluctuation of a transmission signal level by providing a changeover means switching the quantity of an output impedance to an SEPP type power amplifier transmitting an AC control signal superimposed on a signal through a DC power supply cable. CONSTITUTION:An AC control signal (f) is superimposed on a DC signal from transceivers 2A, 2B through a cable E applying DC power from a main controller X to a remote controller Y so as to apply transmission/reception mutually. A final stage transmission section 2c of a transmission section 2a of the devices 2A, 2B consists of the SEPP type power amplifier section 2d consisting of transistors (Trs) Q1, Q2 and an enable circuit 2e using an output of the amplifier section 2d and switching the quantity of impedance to coupling capacitors C1, C2 to the cable E. When a control input to the circuit 2e is at H level, Trs Q3, Q4 are turned on, the AC signal (f) is sent to the Trs Q1, Q2 to bring the output of the Q1, Q2 to a low impedance. When the input B reaches an L level, the Q3, Q4 are turned off and the Q1, Q2 are turned off to obtain a high output impedance.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention can be applied to either a main controller as a remote controller provided on an equipment side such as a gas hot water supply facility, or a remote controller provided on a hot water faucet side. A 2-wire remote controller system that allows control signals to be communicated on both sides (commonly supplied power) from the main controller's DC power supply via a 2!1m cable for power supply A two-wire IJ remote control system configured to bidirectionally communicate control signals (words and signals) between a plurality of remote controllers and a main controller using AC signals superimposed on the two-wire power supply cable. Regarding.

[Conventional technology]

This kind of two-wire remote control system mentioned above is
When connecting the main controller and remote controller, the connection (in order to reduce the number of signal wires, an AC signal is superimposed on the power supply cable to the remote controller, and the power supply cable is passed to the remote controller. The main controller is configured to supply power and to bidirectionally communicate information such as control signals between the main controller and the remote controller using superimposed alternating current signals.

Therefore, each controller requires a pair of transmitting/receiving devices for receiving and transmitting communication AC signals superimposed on the same cable.

This transmitting/receiving device must be designed with consideration to its receiving sensitivity to prevent malfunctions caused by the number of remote controllers connected to the cable and acting as a load, the cable length, its transmission loss, or noise entering the cable. .

[Problem that the invention seeks to solve]

However, as the number of remote controllers increases or the cable length increases, the load increases and the level of the received signal decreases, so unless the reception sensitivity is set to a certain level, normal communication will not be possible. However, if the reception sensitivity is set too high, there is a problem that malfunction may occur due to noise mixed into the cable. Therefore, there is a limit to the setting of reception sensitivity, and it has not been possible to increase the sensitivity very much.

In addition, since the transmitted signal itself is attenuated by the cable load and the number of connected controllers, it is necessary to increase the transmitted output to some extent, but the level is limited by the DC power supply voltage for power supply, so there is a limit. be. Furthermore, if a remote controller is added later, the waveform distortion of the transmitted signal increases due to the increased load, resulting in transmission errors and the distortion components generating harmful noise.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to reduce the decrease in the transmit signal level due to the addition of remote controllers or cable length, and to increase the degree of freedom in setting the receiving sensitivity.

[Means for solving problems]

A feature of the two-wire remote control system according to the present invention is that, when a communication AC signal is superimposed on the power supply two-wire cable, the transmission terminal section of the transmitting/receiving device that transmits and receives this AC signal is connected to the power supply cable. The power amplifier is constructed of a SEPP type power amplifier equipped with a means for switching the coupling impedance for the two-wire cable between high and low levels, and its functions and effects are as follows.

[For production]

In other words, by transmitting a communication AC signal transmitted by a power supply cable using a SEPP format (single-ended push-pull operation format) power amplifier that can make its output impedance extremely low, In addition to suppressing the drop in output signal level due to load fluctuations, this power amplifier output is virtually disconnected from the cable during reception by means of switching the coupling impedance to the cable between high and low levels, so that the transmitter does not become a load during reception. It is to make it.

〔Effect of the invention〕

In other words, since the communication AC signal is transmitted by a SEPP type power amplifier with a low output impedance, even if there is a load change due to an increase or decrease in the number of load controllers or the connection cable length, the transmission signal level fluctuation is reduced.

In addition, since the output of the power amplifier can be virtually disconnected from the cable during reception, it is possible to prevent the output of the power amplifier that constitutes the transmitter from becoming a load on other transmitters. Signal level fluctuations can be reduced.

Therefore, during transmission, the output of the low-impedance power amplifier is coupled to the cable, so the impedance of the cable, which is the signal transmission path, is lowered, suppressing attenuation due to load, and making it difficult for noise to enter the cable. This increases the noise margin of the receiver, making it easier to set the receiver sensitivity.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

As shown in FIG. 1, the output of the DC power supply (1^) of the main controller (χ) functions as a filter for cutting off the communication AC signal (f), and also functions as a filter for cutting off the communication AC signal (f).
) is connected to the hot side (Eh) of the two-wire power supply cable (E) via the inductance (Lυ) to prevent the AC signal (f) from becoming a load on the communication AC signal (f), and the cold side (Ec) is grounded, and power for operation is basically supplied to the remote controller (Y) side via this two-wire power supply cable (E). , ) and the hot side (Rh) of the cable (E) are capacitively coupled to the connection point (α) via a capacitor (C8) to the transmission/reception device (2A) for the communication AC signal (f), and the two wires are While power is being supplied to the remote controller (Y) via the power supply cable (E), data and information are sent to the control device (3A) using the communication AC signal (f) superimposed on the power supply cable (E). It is configured to be able to transmit control signals in both directions.

On the other hand, on the remote controller (Y) side, a diode bridge (DB) and the main controller (X)
Similarly to the side inductance (Lυ), the inductance (L
2), a power supply device (IB) is connected to the power supply cable (E) so that power for operating the remote controller (Y) is obtained from the power supply device (IB), and the On the side of the main controller (X), connect the remote controller (Y) to the connection point (β) between the diode bridge (DB) and inductance (L2) via the capacitor (C2) to the remote controller (Y) and the survey receiver (2B).
are capacitively coupled, thereby supplying power from the main controller (X) to the remote controller (Y) via the two-wire power supply cable (E), while transmitting the superimposed communication AC signal (f). The main controller (
X) side control device (3A) and remote controller (Y)
It is configured to be able to transmit data and control signals in both directions with the side control device (3B).

By connecting another remote controller (Y) in parallel to the two-wire power supply cable (E), it is possible to connect not only multiple remote controllers (Y) and the main controller (X) but also multiple remote controllers. Controller (Y
) can also be configured to enable bidirectional communication.

The operation of the diode bridge (DB) will be explained below.

That is, if the polarity of the power supply cable (E) is connected correctly, as shown in FIG. 2 (A),
The connection between the remote controller (Y) side power supply device f (IB) and the cable ( The hot side (Eh) of E) is connected, and the ground potential is connected to the cold side (Eh) through one third diode (D,) connected to the ground potential.
Ec). On the other hand, the power supply cable (
If the polarity of E) is reversed and connected, the connection shown in Fig. 2 (
As shown in II), the diode bridge (DB)
The remote controller (Y) side power supply (IB) and the hot side (Rh) of the cable (E) are connected through the other fourth guide (04) connected to the connection part (β) of the The other first diode (D
, ), the ground potential is connected to the cold side (Ec). Therefore, no matter how the polarities of the two power supply cables (E) are connected, power is normally supplied to the power supply device (1b) on the remote controller (Y) side, and the cable (B) ) There is no need to consider the connection polarity of the remote controller (Y).

Furthermore, the relationship between the transmitter/receiver (2B) connected to the diode bridge (DB) via the capacitor (C2) and the hot side (Rh) of the cable (E) is automatically maintained, and the cable The connection polarity of (E) does not affect the transmission and reception of the communication AC signal (f) superimposed on the hot side (1!h) of this cable (E).

Next, the operation for bidirectional communication between the main controller (X) and the remote controller (Y) will be described.

In other words, when transmitting data from the main controller (X) to the remote controller (Y), the main controller (X) is connected to the survey receiver! (2A) from the capacitor (C
The alternating current signal (f) sent through I) is transmitted to the remote controller (Y) via the second diode (D2) or the fourth diode (D4) and the capacitor (C2).
The input current is input to the survey receiver (2B), and the input current is transmitted to the main controller (X) via the third diode (D, ) or the first diode (0+).
A closed loop returning to A) is formed. Then, the DC component (■
. ) due to changes in AC signal (f) (±■
+), the AC signal (f) is separated and extracted as a voltage signal (vl). In addition, when transmitting from the remote controller (Y) to the main controller (X), the current change (±
The same is true except that the direction of b) is reversed.

By the way, the diode bridge (DB) is an element that causes signal transmission loss to both the transmitting and receiving devices (2A) and (2B), but the power supply current (Io) is constantly flowing through the diode bridge (DB). Since it is flowing, it is completely conductive and almost no voltage fluctuation occurs between its input and output, so the transmission loss for the AC signal (f) can be almost ignored.

As shown in FIG. 3, the transmission final stage section (2c) of the transmitting/receiving device (2A), (2B) consisting of the transmitting section (2a) and the receiving section (2b) is an NPN transistor (Q).
A linear power amplifier (
2d) and the 0N10FF that supplies power to this power amplifier (2d) using two transistors (Ql) and (Q
4) by controlling the power amplifier (
An enable circuit (2d) as means for switching the impedance of the coupling capacitor (CI) and (Cm) of the output (Op) to the cable (E) from low to high.
It consists of e).

Then, when the control input (B) of the enable circuit (2e) becomes "H" level, the two transistors (Q2) and (Q4) are turned on, and the complementary connected transistors (Qa, (Qz)) are turned on. The transmission AC signal (f) input to the commonly connected base side
) is current amplified and output, and the control input (B) is “
When the level becomes L”, the two transistors (03)
, (Qa) are turned off, and both transistors (Qa) are complementary connected.

When (Q2) is turned off, the output (Op) operates to have a high impedance.

Further, to configure the power amplifier (2d), as shown in FIG. 4, current amplifying transistors (Qs) and (Q-6) are respectively connected to the complementary-connected transistors (Ql) and (QZ). Additionally, the current output capability may be further increased and the output impedance may be lowered.

Further, the power amplifier (2d) is configured in SEPP format. In addition to the configuration in which the NPN type transistor (Ql) and the PNP type transistor (Q2) are connected in a complementary manner, the configuration may be configured using only one type of transistor, NPN type or PNP type, and furthermore, it may be configured using only one type of transistor, such as an FET. It may be composed of elements of the form.

Note that when two-way communication is performed using the communication AC signal (f) superimposed on the power supply cable (E), when one of the transmitter/receivers (2A) and (2B) is in the transmitting state, The AC signal (
f) is amplitude-modulated and used in a half-duplex serial transmission format. And, as shown in Figure 5,
The state where the AC signal (f) is output is "H" level,
The state in which the AC signal (f) is not output is set to the "L" level, and communication data is serially transmitted in digital format, and the contents are discriminated within each control device (3A) and (3B). It sends and receives control signals and data.

Furthermore, by configuring the power amplifier (2d) as a linear amplifier, it is possible to transmit a signal with little loss regardless of the waveform of the transmitted signal, so there is no need to change the configuration of the electric power amplifier (2d). It can easily accommodate various modulation methods for transmitting communication signals.

[Brief explanation of drawings]

The drawings show an embodiment of the two-wire remote control system according to the present invention, and FIG. 1 is a block diagram showing the overall configuration, FIG. 4 is a circuit diagram showing the configuration of the transmission final stage, FIG. 4 is a circuit diagram showing the configuration of another embodiment of the power amplifier, and FIG.
The figure is an explanatory diagram of transmission signals on the cable. (X)... Main controller, (Y)...
...Remote controller, (E)...2IA cable for power supply, (F)...AC signal for communication, (2A). (2B)...Transmitting/receiving device, (2c)...
- Transmission final stage section, (2d)...Power amplifier.

Claims (1)

[Claims] Between the main controller (X) and a plurality of remote controllers (Y) that are supplied with power from the DC power supply (1A) of the main controller (X) via the two-wire cable (E) for power supply, 2-wire cable (E)
A two-wire remote control system configured to bidirectionally communicate a control signal using an alternating current signal (f) superimposed on the power supply cable (E).
), the transmission terminal section (2c) of the transmitting/receiving devices (2A) and (2B) for transmitting and receiving this AC signal (f) is connected to the power supply two-wire cable. (
A two-wire remote control system consisting of a SEPP-type power amplifier (2d) equipped with means for switching the coupling impedance to E) between high and low.