Data frame settings for serial communication

To know more about this subject, please refer to this site.

Arduino Serial library supports several data frames apart from the common 8N1. This is accomplished through the begin method. This is fully discussed in the previous link.

I've modified my library in order to support this. There is also a new example for an Slave, which has 19200 baud, 8 data bits, even parity plus 1 stop bit.

This is exactly the same for a Modbus Master.

/**
 *  Modbus slave example 2:
 *  The purpose of this example is to link a data array
 *  from the Arduino to an external device.
 *
 *  Recommended Modbus Master: modpoll
 *  http://www.modbusdriver.com/modpoll.html
 */

#include <ModbusRtu.h>

// data array for modbus network sharing
uint16_t au16data[16] = {
  3, 1415, 9265, 4, 2, 7182, 28182, 8, 0, 0, 0, 0, 0, 0, 1, -1 };

/**
 *  Modbus object declaration
 *  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
 */
Modbus slave(1,0,0); // this is slave @1 and RS-232 or USB-FTDI

void setup() {
  slave.begin( 19200, SERIAL_8E1 ); // 19200 baud, 8-bits, even, 1-bit stop
}

void loop() {
  slave.poll( au16data, 16 );
}