FredHS

Hi,

I am looking for a way to connect 2 external switches to my x3 (and x50v). I have not made any progress with my original idea of using the USB DATA+ and DATA- lines. I therefore attempted to use the DSR and CTS lines (x3 pins 19 & 16) directly at the connector (no level shifter or other circuitry connected). Normally, the DSR line has a H (3.3V) level. When I boldly ground the DSR pin, the following call

DWORD dwstatus;
GetCommModemStatus(hport, &dwstatus);

(hport previously set with CreateFile(..)) will always reveal that the bits MS_RLSD_ON **and** MS_DSR_ON are set. Changing the level of the CTS pin does not appear to have any effect on dwstatus; when I let DSR float again, both MS_RLSD_ON and MS_DSR_ON become 0.

When I ground only the DSR pin and query the line status with WaitCommEvent(..), EV_CTS **and** EV_DSR will be set. Again, changing the level of the CTS pin does not appear to have any effect (I did not forget to set both the EV_CTS and EV_DSR bits with SetCommMask(..) ).

Any suggestions?

Thanks,

Fred