Counting Problem

[tkempher]

I have a DL06 PLC with a H0-Ctrio High speed count card. What I am trying to do is set up a system to measure cut marks on a web of paper as it is passing past a high speed mark sensor and counting pulses between leading edges of cut marks. Then scale them counts to give me an accurate output of length be it in inches or millimeters. This is a high speed application as web is traveling at 1000 FPM and I need .002 resolution, as you can see I will need full capability of this input module. About 100khz = 192". Any help that anyone could provide would be deeply appreciated. Thanks!!

[b_carlton]

You haven't said what the resolution of your pulse count generator is. I am going to assume that your '.002' is '.002 inches'. Even at one pulse every .002 inches is indeed right at the 100 khz max on the inputs of the CTRIO.

Looking at the CTRIO Workbench, I'm not sure how to perform the function - one edge of an input starts a count the second edge (possibly wired to another input?) latches the count. I see it for time but not for count.

Maybe the good folks at this site will reply.

[tkempher]

Thanks for replying b_carlton. Yes I am looking for a resolution of .002 in. pr roughly 95,000 pulses per second. I would appreciate any ideas anyone has, even if it is on a different platform. Thanks 

[Darenko]

??

[Greg]

Hi Darenko, I assume the "??" means you are wondering why there are no replies to this post. Sometimes some of the posts slip through the cracks, and this is one we missed. My apologies to tkempher and you.

The CTRIO can count 100KHz (and we are soon releasing a CTRIO2 that can count up to 1MHz). There is a feature on the CTRIO called "Capture" but in tkempher's application, it may not be quick enough if he was going to use it in rapid succession. The reason being once you enable the Capture (with a bit), and the Capture pulse comes along and the CTRIO's counter captures the count, then the Capture feature must be re-enabled to get the next one.

Hope this helps!