i am using a ivt-16 fast input sinking card for a pulse encoder, the pulse happen at a frequency of 2hz the prox switch from the encoder is 24v dc. the problem i'm having is the input starts missing pulses as i approach two pulse a second. even with the sti set to interrupt every two ms and the only thing in the ladder logic being a int and iim it still won't catch the pulses consistently. the l.e.d.s on the front of the input card are flashing in time with the signal that my o-scope is reading. been on the phone double checking with alen bradley support, they just keep saying it should work and now aren't returning calls or e-mails