File content as of revision 0:8864eb729b32:

#include "mbed.h"
 
Serial pc(USBTX, USBRX);
Serial modbus(PB_9, PB_8,9600);//(tx,rx,baud)
 
DigitalOut DE_RE(PB_0);

 
void PC_callback() {
    // Note: you need to actually read from the serial to clear the RX interrupt
    //modbus.printf("PC_callback\r\n");
    modbus.putc(pc.getc());
} 
void MODBUS_callback() {
    //pc.printf("MODBUS_callback\r\n");
    pc.putc(modbus.getc());
}
 
int main() {
    pc.attach(&PC_callback);
    modbus.attach(&MODBUS_callback);
    while(1) {
        
        /*
        if(pc.readable()) {
            modbus.putc(pc.getc());
            pc_activity = !pc_activity;
        }
        */
        DE_RE=1;
        
        modbus.putc(0x01);
        modbus.putc(0x03);
        modbus.putc(0x00);
        modbus.putc(0x00);
        modbus.putc(0x00);
        modbus.putc(0x01);
        modbus.putc(0x84);
        modbus.putc(0x0A);
        //wait(3);
        wait_ms(2);
        DE_RE =0 ;
        /*    
        modbus.putc(0x31);
        //}
        //DE_RE =0 ;
        //wait(0.1);
        
        
        if(modbus.readable()>0) {
            pc.printf("modbus read something\r\n");
            pc.putc(modbus.getc());
        } else{
            pc.printf("modbus read nothing\r\n");
        }
        
        */
        wait(10);
    }
}