Lopy with modbus

[abhishek2101]

Which pins do I need to connect on the board to do modbus ?

[thibault]

@svonbentzel No, for me too. I have use this one for get modbus run fine:
github.com/pycom/pycom-modbus/tree/master/uModbus

[Eric73]

@svonbentzel No, i dont know witch which pycom board your talking about, but ESP32 RX/YX pin are 3.3V TLL level, modus is RS422 or RS485 or RS232. RS422 and RS485 are very close electrical level (on a differential line), RS232 is +12V and -12V so you need an adapter and you must choise it to be on same physical level of the sensor you plan to use.

[philwilkinson]

Have anyone had success with this modified modbus library?

[svonbentzel]

can I connect the modbus device directly to the Pycom Board.

or did I need a additional modus RS485 adapter?

[Eric73]

@abhishek2101 RS485 OR RS232 it depend of your sensor.
MAX3232 or SN65HVD10 for exemple is good component.

[abhishek2101]

@Eric73 I will be using Modbus RTU, can you suggest me a good RS485/RS232 transceiver ?

[Eric73]

Hi, in fact it's depends if you do modbus over tcp (so it's wifi and no pin) or modbus RTU using uart pin (and RS232/RS485 transceiver don't use directly your uart pin!) you have selected when you created your modbus object.
According to source code this is an valid example.

uart_id = 0x01
modbus_obj = Serial(uart_id, pins=('P9', 'P10'))

It's seem that pycom documentation lake information about the initialization of this object

[abhishek2101]

can anybody help please ?