====== Modbus RTU Master ======

The MOACON can also function as a Modbus RTU Master to query a Modbus RTU slave.  The following functions are provided and will function at any baud rate above 9600.

^ Function Name     ^ Modus Function Code  ^
| [[:moacon:rtu_readcoils:|RTU_readCoils]]     | 1, 2                 |
| [[:moacon:rtu_readregs:|RTU_readRegs]]  | 3                    |
| [[:moacon:rtu_readinregs:|RTU_readInRegs]]  | 4                   |
| [[:moacon:rtu_writecoil:|RTU_writeCoil]]  | 5                    |
| [[:moacon:rtu_writereg:|RTU_writeReg]]  | 6                    |
| [[:moacon:rtu_writecoils:|RTU_writeCoils]]  | 15                    |

Use [[:moacon:opencom:|openCom]] to open a serial port before calling the functions.

<code c>
#include "moacon500.h"
void cmain(void)
{
    int i=0,kk;
    u8 res;
    
    static u8 MBcoilBuffer[100];
    static u16 MBregisterBuffer[100];
    
    clcdI2cInit(0);
    clcdPower(1);
    delay(100);
    clcdCsr(0);
    
    openCom(0,57600,C8N1);                          // Open the serial port
    while(1) {
        delay(100);
        res = RTU_writeCoils(0,1,0,0x12);           // Write 1 bit to the Modbus RTU slave
        delay(100);
        res = RTU_readCoils(0,1,MBcoilBuffer,4,12); // Read 12 bits from the Modbus RTU slave
    }
}
</code>

The [[:moacon:getcrc:|getCrc]] function can be used to compute a Modbus RTU CRC if the needed.

[[moacon:index|MOACON - Modular Programmable Automation Controller (PAC)]]