Tecchie

Sorry for the confusion about the IC name and the late response. I haven't been here for a longer while. But Mario kindly helped out.

Also I suggest a couple of resistor on the output wiring. One 1Meg pullup at pin 6, and one 1Meg pulldown at pin 7 (of the 75176). That prevents undefined reception at the receiver side, when there's no enable of transmission.

The transmit enable pin is hardwired to logic high in my example, so transmission is always enabled. So these bias resistors are not necessarily needed here, but one may add them.

The solution is a bit hacked, and delicate, but worthy the same.

Of course, it's a bit of a hack. The two common solutions on a µC would be either to set the break flag in the UART register or decrease the baud rate and send 0x00. Unfortunately both options are not available on the netduino/.NET Micro Framework. The Break property on the SerialPort class is only available in full .NET and changing the baud rate while leaving the port opened isn't allowed (at least when i tested that).

Thomas

    port1.Write(GPSbuffer, 0, GPSbuffer.Length);
    if (GPSbuffer[0] != 36)
        continue;

Those two lines seem a bit strange. First line: Why do you try to write the data back to the GPS?
Second line: are you sure that you want to skip all of the remaining part of the while-loop (including the reading from the IMU)?