JPH02104197A - Serial signal transmitting equipment - Google Patents

Abstract

PURPOSE:To attain normal signal transmission by incorporating signal line polarity switching functions in serial transmission interfaces of respective equipments, preparing two pairs of drivers and receivers belonging to respective polarity and selecting a driver and a receiver having correct polarity. CONSTITUTION:A serial transmission interface 6 is constituted of differential type line driver/receiver ICs 10 to 13 and a receiver output selecting circuit 9. Terminals having respectively different polarity are connected to the outputs of two drivers 10, 11 and terminals having respectively different polarity are connected to the inputs of the receivers 12, 13. At the time of transmitting/ receiving data, a microcomputer 7 selects a driver and a receiver belonging to one polarity. Thereby, a signal line whose polarity is not clear is passed through the driver/receiver ICs 10 to 13, driver inputs 1D, 2D are connected to a TXD of the microcomputer 7, and receiver outputs 1R, 2R are connected to an RXD through a receiver output selecting circuit 9. Consequently, the non-polarity of a signal line connecting terminal can be attained and normal signal transmission can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device using differential serial transmission, such as a serial signal transmission device applied to signal transmission between control devices of air conditioners.

[Prior Art] Typically, for example, an air conditioner is composed of a remote control, an indoor unit, and an outdoor unit. For signal transmission between devices, a two-line crossover wiring system using serial (serial encoded signal) transmission technology has already been put into practical use in order to save wires. This method has recently made it possible to control a plurality of indoor/outdoor units with one remote controller.

FIG. 4 is a diagram showing the basic configuration of a conventional serial transmission/two-line crossover wiring. Further, as an example of a serial transmission interface, FIG. 5 shows a conventional differential transmission circuit diagram.

In FIGS. 4 and 5, a remote control 1 is connected to indoor units 2a, 2b and outdoor units 3a, 3b via crossover wiring 5, and centrally controls/monitors the air conditioning system.

Each device has a serial transmission interface 6',
When the microcomputer 7 performs transmission/reception, the control signal D of the differential line driver/receiver IC 8 is used.
E, controls RE.

[Problem to be solved by the invention] In FIG. 4, the two lines of the crossover wiring 5 have polarity, and A
The wire/B wire must be securely connected to the A terminal/B terminal of the signal terminal 4 of each device. Conventionally, there has been a problem that when A/B are connected in reverse, normal signal transmission is impossible and the air conditioner cannot be operated normally.

SUMMARY OF THE INVENTION An object of the present invention is to provide a serial signal transmission device that can solve the above-mentioned conventional problems.

[Means for Solving the Problems] A serial signal transmission device according to the present invention is a serial signal transmission device that bidirectionally transmits signals between a plurality of control devices using two transmission lines with determined polarities. The present invention is characterized in that two sets of differential drivers and receivers are provided in the serial transmission interface of each control device, and driver outputs and receiver inputs of the two sets of drivers and receivers having different polarities are connected.

[Effect]

According to the present invention, for example, by incorporating a signal line polarity switching function into the serial transmission interface of each device, preparing two sets of drivers and receivers belonging to each polarity, and selecting the driver and receiver with the correct polarity, normal operation can be achieved. This enables signal transmission.

[Embodiment] FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing its operating waveforms.

In Figure 1, 1 is a remote control, 2a and 2b are indoor units, 3a and 3b are outdoor units, 4 is a signal line connection terminal block, and 5
is a signal line, 6 is a serial transmission interface, 7 is a microcomputer, 9 is a receiver output selection circuit, 10
．． 11 is a differential line driver, and 12.13 is a differential line receiver.

In FIG. 1, the serial transmission interface 6 is
It is composed of differential line driver/receiver ICs 10 to 13 and a receiver output selection circuit 9. The outputs of the two drivers 10.11 are terminals IY and 2Z with different polarities.
, IZ and 2Y are connected. The inputs of the receivers 12 and 13 are connected to terminals IA and 2B, and terminals 1B and 2A, which have mutually different polarities.

When the microcomputer 7 transmits/receives data, it selects drivers and receivers (eg, driver 10 and receiver 12) belonging to one polarity. As the selection (polarity switching) means, the control signals IDE, 2DE and S
Use.

The signal line 5 of unknown polarity is connected to the signal line connection terminal block 4,
Passes through differential line driver/receiver ICs 10 to 13, and the driver ID and 2D are microcomputer 7.
The receiver outputs IR and 2R are connected to RXD of the microcomputer 7 via a receiver output selection circuit 9.

In FIG. 2, after power-on, the device 9 transmits data according to predetermined rules.

Other devices receive the data, judge whether or not the data has been received correctly, and if it is not received correctly, determine that it is a reverse polarity connection, and use the control signal S to output the receiver output IR,
Switch the selection of 2R. Here, an error detection code (generally used is a parity code or a cyclic code) is added as a material for determining whether or not the data has been received correctly.

When the data is received correctly, the device determines that the correct polarity has been selected.

This series of operations determines the polarity of all devices.

When transmitting data, the microcomputer 7 controls the driver belonging to the selected polarity using the control signal IDE (POI), 2
Select and use DE (PO2).

FIG. 3 shows an operation flowchart up to polarity determination in one embodiment of the present invention.

In FIG. 3, after the power is turned on, each device generates a random transmission waiting time Tw. If data is received from another device during the waiting time TW, it will determine whether the data was received correctly or not, and if there is no data from the other device, it will send the data after a waiting time of 1w. .

Here, the counter C0RRECT C0UNTER belongs to when data is received normally and when it is not.

INcORREcT, C0IJNTER, and their values (here, the counter value -2) are used as a criterion for determining polarity and switching polarity.

[Effects of the Invention] According to the present invention, it is possible to make the signal line connection terminals of each device non-polarized, and the signal line connection work during installation wiring work can be significantly reduced. In addition, there will be no malfunction of each device due to incorrect connection, and reliability can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a serial transmission interface circuit for an air conditioner as an embodiment of the present invention, FIG. 2 is an operating waveform diagram of the embodiment shown in FIG. 1, and FIG. 3 is an implementation of the embodiment shown in FIG. 1. An example operation flow diagram, FIG. 4 is a basic configuration diagram of serial transmission of a conventional air conditioner, and FIG. 5 is a circuit diagram of a serial transmission interface of a conventional air conditioner. 6... Serial transmission interface, 9... Receiver output selection circuit, 10.11... Differential type line driver, 12.13... Differential type line conflict receiver. Applicant's agent Patent attorney Takehiko Suzuichi Figure 3

Claims (1)

[Claims] In a serial signal transmission device that performs bidirectional signal transmission between multiple control devices using two transmission lines with fixed polarities, each control device has two sets of differential drivers and receivers in its serial transmission interface. 1. A serial signal transmission device comprising: a driver output and a receiver input having different polarities of the two sets of driver and receiver, respectively, connected to each other.