Hello Everyone,
I use the LM628 as a counter to read pulses from incremental quadrature encoders. Then it sends the value of the instantaneous position to an HC11 to close a position control loop. The system worked and still Works fine for a lot of cases but when I use it with the extensometer MFL-300B, it sometimes fails. The LM628 counts spurious pulses and thus the system indicates movement when it is actually still. This type of extensometers has a normal differential RS422 TTL output. I use an AM26LS32AC integrated circuit to convert from differential to single-ended and then I send that to the LM628.
The curious thing is that when I use the NI-6210 acquisition card from National Instruments to read the pulses from the same extensometer, it works fine and it doesn't absolutely fail. I mean that when the xtenosmeter is stationary, sometimes it sends spurious pulses and the NI-6210 doesn't count those pulses. I gues that this is because they are not in quadrature. But I don't understand why on the other hand, the LM628 counts these spurious and random pulses although they are not in quadrature.
I look forward to hearing from anybody.
Best regards,