TTL suddenly not sending - I/O test not working

Hi - I have been running a study with DirectRT and an ASL Eyetracker. The experiment was working properly for some time - sending TTL signals to the eyetracker with them being accurately received. However, at some point the signals stopped sending. In some of our ASL files it seems that the port was working but the different signals were not received (all 0s instead of numbers ranging from 1-150). However, eventually no signals at all were being received. I have used the I/O test, entering 888 for the port and 100ms, and it is not working. Because of this, I assume the problem is with the DirectRT computer. I checked the device manager and it says that COM1 is working properly. I don't understand what would have caused it just to stop sending at some point, and I have been unable to fix the problem. Any ideas? I haven't seen a detailed troubleshooting section describing possible fixes, so I am hoping you can offer some suggestions.

Thanks,
Melanie

Hi Melanie,

I believe we've been in email contact with one of your colleagues.

One thing to consider is that Port 888 matches up with your computer's parallel port, which COM1, a serial port, would have a different port number - typically 1016.

If this is in fact a separate issue, please reply back and we'll help you sort it out.

JEC