Hi Baturin,
It is quite possible that your BNC connector has problems. If you were able to route the output of Counter 0 to a PFI line, and able to see a good signal, then your terminal block is at fault. The first things you should look for are the pins. Sometimes, the pins on the connectors are bent, and thus do not provide a reliable contact. Second thing you should look for is any external damage. Finally, use the test panel in Measurement and Automation Explorer (MAX), in the counter tab to test the card (which is probably what you are already doing).
If all of the above still seem to confirm your initial diagnostic of a bad BNC connector and a good M series card, then please call us. We would then do a final troubleshooting before sending your BNC connector back to be repaired.
Thank you and best regards,
Nathan
________________
Applications Engineer
National Instruments