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MODBUS with Handshake

Monte Apr 2, 2024 06:28 PM


Is it possible to use some kind of handshake with the ModbusClient instruction? Will say a digital port which is high when the logger is sending data and low when the logger is listening on the RS485 bus.

I need to communicate with sensors with 460800bps. I have an RS485 baud-converter which translate from 115200 to 460800bps. Up to 230400bps it works fine with automatic half duplex. At 460800 the direction of dataflow must be set using an input pin of the converter. When the input pin is set high, the ModbusClient instruction can send the request form the logger to the sensor, then the pin must set low for receiving the answer from the sensor.

Of course, if someone knows an RS485 converter 115<->460kbps doing the job without handshake, this would a good solution too.

optimalobeisance Apr 3, 2024 09:10 AM

Yes, it is possible to use a handshake mechanism with the ModbusClient instruction to control the data flow when communicating with sensors via RS485 at 460800bps. doodle baseball

In your case, you have an RS485 baud converter that requires a specific input pin to control the direction of data flow. When the input pin is set high, you can use the ModbusClient instruction to send the request from the logger to the sensor. Once the request is sent, you need to set the input pin low to enable reception of the answer from the sensor.

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