I need to acquire analog input data that is correlated with position information from an incremental encoder. In an old DOS system we do this by having the processor respond to fast timer interrupts. On each interrupt, the processor reads the encoder position from a 5312 encoder board and if the position has advanced to the next increment, it does a single analog read which is saved in a buffer. In a Windows environment, we are looking at using one phase of the encoder as an external trigger to the A/D board, which is acquiring a whole buffer using DMA, so the processor would not be involved in a real-time fashion. But this method has a problem. In our application it is possible for our encoder to briefly reverse direction during the data acquisition. Merely counting pulses from one phase of the encoder will not properly take this brief reversal into account, because the direction information is not available in one phase. We could build a custom interface board with a microcontroller to generate unidirectional pulses from quadrature encoder input, but we would rather use all off-the-shelf hardware. Is there any solution to this problem using commercial PCI-bus boards?
-Robert Scott Ypsilanti, Michigan (Reply through this forum, not by direct e-mail to me, as automatic reply address is fake.)