robertmee: Good question. There is about 0.8mm between increments and 1.1ms. If I expand that to 2 ms then the range per pulse would increase to 1.6mm. This might work. The only other issue was that when we previously checked on it, the time delay for the I/O increased as we added expansion modules and we needed 3 or 4 modules. You've given me some things to consider. Thanks,