I assume that you mean the RS-232 module when you say “serial module”.
You have not posted any code, so I can not comment on how you are reading and writing to the module.
I would start diagnosis by doing a loopback test. I would put a jumper wire between the RX and TX pins of the RS-232 connector and then write a small program that writes a few bytes and then reads. If I am able to read what I sent, then the module and code are functioning properly.
We are lucky that we had another rs232 module lying around, the first one was faulty, no reaction when i placed the wire(staple) between the two pins.
The second one worked like a charm… thank you very much mike!
EDIT: In the end it wasn’t the module anyway, it was the gadgeteere cable that wasn’t working, replaced it and now both work. Sometimes it can be so easy and our problem is that we think to complicated
OK, back to the beginning, the event doesnt fire anyway, it only fired when I placed a wire between the RX and TX pins.
The thing that gets me is, that it shows that there is data available, but the event is not fired…tried it on a hydra 4.1 and a cerberus 4.2.