A Constant Current Diode Circuit for Instrument Bus Slave Device Interface

Abstract

The invention discloses a current regulative diode circuit of a meter bus slave interface. The current regulative diode circuit of the meter bus slave interface comprises a bridge rectifier circuit, a constant current circuit, a data receiving circuit and a data sending circuit. The two input ends of the bridge rectifier circuit are used for being connected with two transmission lines of a meter bus respectively. The first output end of the bridge rectifier circuit is respectively connected with the input end of the constant current circuit and the data receiving circuit. The constant current circuit comprises at least one current regulative diode. The output end of the constant current circuit is connected to the second output end of the bridge rectifier circuit through a switch circuit. The data receiving circuit is provided with a data receiving port and is used for receiving data. The data sending circuit is provided with a data sending port and is used for sending data. The control end of the switch circuit is connected with the data sending circuit and is used for controlling switching-on and switching-off of the switch circuit according to the data sent by the data sending circuit.

Description

technical field [0001] The invention relates to a slave device interface circuit of an instrument bus, in particular to a constant current diode circuit for an instrument bus slave device interface. Background technique [0002] Meter Bus (M-bus for short) is a new type of bus structure, which is characterized in that only two non-polar transmission lines are used as power supply lines and transmission lines for serial data transmission at the same time, and each terminal device is confirmed by a different address code It can be connected to the M-bus in parallel. Such as figure 1 As shown, the master device actively starts a communication process, that is, sends instructions and data, and the slave device monitors the bus as a slave device, and is ready to respond to bus commands at any time. [0003] The M-bus chip is suitable for all kinds of consumer instruments, such as water meters, electricity meters, gas meters and smoke alarm devices, etc., and can be widely used ...

AI Technical Summary

Problems solved by technology

At present, the m-bus slave interface circuit generally uses the TSS721 interface chip of American TI Company, which is not only expensive, but also inconvenient to purchase

[0004] As another example, the FG722 chip of Xi'an Shenya Electronics Co., Ltd. is a substitute chip for the TSS721 interface chip. It is a meter bus dedicated terminal transceiver chip designed according to the Meter-Bus communication standard (EN1434-3), as a slave and M-BUS bus interface chip, so there are also problems of high cost and inconvenient use

[0005] In addition, there are circuits using discrete components, but there are problems such as difficult debugging and production, insufficient stability, poor consistency, serious temperature drift, and high cost.

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