Surbyte
commented
5 years ago You ddn´t understand how to inicialize the constructor. Modbus(uint8_t u8id, uint8_t u8serno, uint8_t u8txenpin);
- u8id : node id = 0 for master, = 1..247 for slave
- u8serno : serial port (use 0 for Serial)
- u8txenpin : 0 for RS-232 and USB-FTDI
- or any pin number > 1 for RS-485
- uint8_t u8serno; //!< serial port: 0-Serial,
- 1..3-Serial1..Serial3; Mega/DUE x ejemplo
- 4: use software serial
- uint8_t u8txenpin; //!< flow control pin: 0 =USB or RS-232 mode, >0 =RS-485 mode
When you casually invert the configuration it works but why? Because you have placed RS485_pin whose value is 4 as a port type and that is what corresponds to SoftwareSerial and u8txenpin is pin 1 same as TX of Serial. Your master config must be Modbus master(ID, 4, RS485_pin); // So simple!!
Hi, Thank you for this library and the examples. I have a question.
include
include
define rxPin 2
define txPin 3
define mySerial Serial1
define ID 0 // 0 = Master > Slave ID
define Port 1
define RS485_pin 4
SoftwareSerial mySerial( rxPin, txPin )
master.begin( 38400, SERIAL_8E1 )
why this does not work?
and if you change
// Address, Serialport, Pin for RS485 (DE/RE) Modbus master(ID, Port, RS485_pin); // this is master and RS-232 or USB-FTDI
to
// Address, Pin for RS485 (DE/RE), Serialport Modbus master(ID, RS485_pin, Port); // this is master and RS-232 or USB-FTDI
you could use RS485 Half Duplex on SoftWareSerial easier.