Problem with communicating with STAMP through serial port

[Skabana159]

Our team's been trying to build a custom circuit board that provides extra sensory information to the STAMP. However, we've been encountering troubles with the SERIN command in STAMP. It seems that the STAMP sends an echo byte of its own whenever output is processed through the serial. Does anyone have a similar problem like this?

[rbayer]

You are correct, the Stamp echos everything that is sent to it. Unfortunately, there is no way around this.

[Skabana159]

I just realized what I type doesn't quite make sense.

Basically, we have another microcontroller on the circuit board which process the readings from sensors and send them to the STAMP through the serial port.
We programmed the STAMP to send an handshake byte to the microcontroller, which upon receiving the byte, sends over the sensor readings. We have the baud rate set at 9600. However, what is interesting is that whenever the STAMP receives the data, it sends an echo byte to the microcontroller. I don't know if this is the reason why we are having serious problem.
We have checked each subsystem with a terminal program and they all work fine on their own. The problem is when we attach the two serial ports together.