REXYGEN Community Forum

contactform

Member

Registered: 2015-10-30

Posts: 45

Monarco HAT RS485 configuration for Modbus

How to set baudrate of RS485 on Monarco HAT for Modbus communication?

Thanks!

jaroslav_sobota

Administrator

Registered: 2015-10-27

Posts: 535

Re: Monarco HAT RS485 configuration for Modbus

In order to use the onboard RS485 of the Monarco HAT, it is important to understand the internal structure of the Monarco HAT. The Raspberry Pi is talking to the Monarco HAT's MCU via UART and it's the MCU who is talking to devices over the RS485 line. See details in the Monarco HAT hardware reference manual.

The UART settings are fixed: /dev/ttyAMA0, baudrate 115200, no parity, 1 stopbit and that's what you should set in Modbus configuration dialog, regardless of the settings in individual devices on RS485 line.

The properties of the RS485 line are defined by parameters of the Monarco HAT I/O driver. These parameters should correspond with the settings in your devices (e.g. baudrate 9600). See the Monarco HAT I/O driver manual for more details.

Jaroslav

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