[..]I have been fighting this problem for a while now and tried the following:1) I first tried the raw encoder signal, but then added the Schmitt trigger, increased the signal strength of the encoder lines by adding resistors to ground, double checked my shielding, etc...[..]If anybody out there has some recomendations, I am open to anything.
is you schmit trigger out tied directly to PFI and the ground from ST directly to digital ground of your board?
I'm also curious about your 2V level, since the ST output FET will be smoked being low and pulled up with 2V ...ah which ST do you use?
Pg 14 on this App Note may be describing your situation using a buffered chip. Do you have any of the unbuffered (UB) versions?
What were the results when you fed the encoder directly into the counter?
Your straw grasping is close to the mark. The application used in an engine test cell with a 200 Hp DC motor as well as the ingition system of the gasoline engine. My first guess was that this was the problem and I proceeded to shield everything and reroute cables to get some distance between my signal wires. I'm 99% sure that this is not the noise source.
The strongest evidence (to me anyway) is that the problem does not show up when the DAQ is not connected. I can scope the signal and it looks perfect, as soon as I hook up the line to the DAQ I can see the noise blips.
Thanks for the extra brain-power.