I would like to communicate via Modbus RS485 between an arduino pro portenta machine control card and a Schneider Lexium32M servo driver, the problem is that I manage to report an "Invalid argument" error via the ModbusRTUClient.lastError() function of the ArduinoModbus.h library
but no idea of how put the "good" argument because even when I use a sample program all done without changing anything I get the same error.
If you can help me find the right "synthax" or even find a piece of Modbus code that is able to call the function: R/W Coils R/W handling register etc...
/*
Modbus RTU Client Toggle
This sketch toggles the coil of a Modbus RTU server connected via RS485
on and off every second.
Circuit:
- MKR board
- MKR 485 shield
- ISO GND connected to GND of the Modbus RTU server
- Y connected to A/Y of the Modbus RTU server
- Z connected to B/Z of the Modbus RTU server
- Jumper positions
- FULL set to OFF
- Z \/\/ Y set to ON
created 16 July 2018
by Sandeep Mistry
*/
#include <ArduinoRS485.h> // ArduinoModbus depends on the ArduinoRS485 library
#include <ArduinoModbus.h>
#include "Arduino_MachineControl.h"
using namespace machinecontrol;
void setup() {
Serial.begin(9600);
while (!Serial);
Serial.println("Modbus RTU Client Toggle");
comm_protocols.init();
comm_protocols.rs485Enable(true);
comm_protocols.rs485.begin(9600, 0, 500);
comm_protocols.rs485.receive();
// start the Modbus RTU client
}
void loop() {
if(ModbusRTUClient.holdingRegisterRead(0x0178)== -1){
Serial.println(ModbusRTUClient.lastError());
}
Serial.println(ModbusRTUClient.available());
// wait for 1 second
delay(1000);
}
