Hi everybody,
I'm tryng to read the Modbus registers of a N1200 (Novus) through RS485.
I'm using an Arduino Mega and a Max485 adapter.
My code is:
#include <ModbusMaster.h>
#define MAX485_DE 2
#define MAX485_RE_NEG 5
// instantiate ModbusMaster object
ModbusMaster node;
void preTransmission()
{
digitalWrite(MAX485_DE, 1);
digitalWrite(MAX485_RE_NEG, 1);
}
void postTransmission()
{
digitalWrite(MAX485_DE, 0);
digitalWrite(MAX485_RE_NEG, 0);
}
void setup()
{
pinMode(MAX485_DE, OUTPUT);
pinMode(MAX485_RE_NEG, OUTPUT);
// Init in receive mode
digitalWrite(MAX485_DE, 0);
digitalWrite(MAX485_RE_NEG, 0);
// Modbus communication runs at 9600 baud
Serial.begin(9600);
// Modbus slave ID 1
node.begin(1, Serial);
// Callbacks allow us to configure the RS485 transceiver correctly
node.preTransmission(preTransmission);
node.postTransmission(postTransmission);
}
void loop()
{
int Mdelay = 150; // microdelay
// node.readHoldingRegisters(Adress, Cantidad de registros);
node.readHoldingRegisters(0x0000, 3);
/* node.writeSingleRegister() */
Serial.println(node.getResponseBuffer(0));
Serial.println(node.getResponseBuffer(1));
Serial.println(node.getResponseBuffer(2));
/*char sp = Serial.read();
Serial.println(sp);*/
delay(Mdelay);
node.clearResponseBuffer();
}
The problem is that the serial print shows me error characters (squares )in the first register before the correct value (See image).
I tried with Arduino Mega and Nodemcu (ESP8266) and both have the same problem.
The problem is always with the first register i read, whichever it is.
I think is a library problem but i don't now how to fix it.
From already thank you very much
