Hi All. I have a very specific question about tracking using an encoder and bitshift register. We would like to use a Compact or Control Logix PLC but when we tried a few years ago (>5) I found that we couldn't get it to work as well as the ML1400. It was limited by the I/O scan time. On the ML1400 we track multiple objects (>300) at up to 1000 increments a second with 20480 bits (5 x 4096). We also have numerous devices attached where we check the time and distance between events. I would like to keep the 1ms cycle time and if possible shift more bits. Is this something anyone else has done? I don't know how to overcome the I/O limitation and mostly just want to know if it is possible but pointers on how to do it in a Compact or Control Logix are appreciated. Thanks, Larry