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emelianov / modbus-esp8266

Most complete Modbus library for Arduino. A library that allows your Arduino board to communicate via Modbus protocol, acting as a master, slave or both. Supports network transport (Modbus TCP) and Serial line/RS-485 (Modbus RTU). Supports Modbus TCP Security for ESP8266/ESP32.

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0x3 error

kurnatskyi opened this issue · comments

commented

There is a device SOCOMEC A40. I'm trying to take readings from it ESP32 + MAX485. Gives error 0x3 illegal value. When taking readings from modbus poll :
Tx: 0F 03 07 04 00 01 C5 91
Rx: 0F 03 02 03 CD 10 E0
In debug serial on ESP32:
3 7 4 0 1
83 3 60 F2
Request result: 0x3
but if I also have a usb-485 adapter in the rs485 line and I just power it up, even from the power supply, then everything is ok. packets go through
Upd - if max485 feed from another source and ground from device connect to esp - its ok