View Single Post
Old September 26th, 2013, 08:11 AM   #2
dmargineau
Lifetime Supporting Member
United States

dmargineau is offline
 
dmargineau's Avatar
 
Join Date: Dec 2011
Location: Midwest
Posts: 2,385
Welcome to the Forum!
I'd first suggest to do a little homework and try comprehending generic systems containing pulse generators (encoders) and pulse counters/readers (High Speed Counter PLC modules).
http://literature.rockwellautomation...n011_-en-p.pdf
http://literature.rockwellautomation...m006_-en-p.pdf

In order to accomplish this task you will need a couple of the missing system's parameters such as the Encoder PPR (Pulses Per Revolution, the roll the encoder is attached to Circumference or the eventual Material Roll Circumference plus the Material Roll to the encoder shaft gearing ratio.
Once acquring of these parameters it is a simple matter of ladder logic computing the number of pulses generated by the encoder when any point of the material contacting roll surface travels one meter and then turning on one of the 1746-HSCE Outputs when the required number of pulses have elapsed.
Unfortunately, after studying the User Manual (especially Pages 1-3 and 2-16) you will probably arrive at the conclusion that your existing system currently uses a Rate operation mode while the task at hand will require a Range operating mode.
Since you cannot use both at the same time, you have two choices.
One would be to split the encoder signal using something like http://www.dynapar.com/uploadedFiles...r%20Manual.pdf; one of the splitter's outputs will be connected to the existing counter and used for the existing Rate (speed)operating mode.
The second splitter output will be connected to an unused 1746-HSCE input channel and this channel will be used in Range operating mode counting the required number of pulses and controlling the module's outputs accordingly.
The second option would be to install a separate encoder, connected to a HSCE channel configured for Range operating mode and use this encoder to compute the material length movement, however, this will require some engineering/currency/labor/time investments.

Last edited by dmargineau; September 26th, 2013 at 08:15 AM.
  Reply With Quote