adccommunitymod (AutomationDirect) asked a question.
Created Date: June 02,2004
Created By: laveryt
**** This post has been imported from our legacy forum. Information in this post may be outdated and links contained in the post may no longer work.****
I'm having some dificulty getting this to do what I want. I have the CTRIO connected to a 600 PPR Encoder that has a 12 " Cir wheel on it. This feeds a "length " into the process. This length is compared to a target or preset when the length is greater than or equal to the preset then I want a pulse out for about 20-50ms to trigger a cutting device. I then want the preset value to increment up to the next value. like this "target is 12 " or 600 pulses when 600 is reached the target now becomes 1200 then 1800 ect. I do not want to reset the count because pulses are lost and that costs acurracy. The measuring wheel never stops rotating as the product that needs to be cut is coming out of an extruder at about 12 ft min. Anybody know how this can be done with the CTRIO? I have done this in the past with the High speed counter inputs at X0 - X3 on the DL05 pretty well. But I have to use them to count another pulse count from a different device.
Created Date: June 02,2004
Created by: laveryt
I'm having some dificulty getting this to do what I want. I have the CTRIO connected to a 600 PPR Encoder that has a 12 " Cir wheel on it. This feeds a "length " into the process. This length is compared to a target or preset when the length is greater than or equal to the preset then I want a pulse out for about 20-50ms to trigger a cutting device. I then want the preset value to increment up to the next value. like this "target is 12 " or 600 pulses when 600 is reached the target now becomes 1200 then 1800 ect. I do not want to reset the count because pulses are lost and that costs acurracy. The measuring wheel never stops rotating as the product that needs to be cut is coming out of an extruder at about 12 ft min. Anybody know how this can be done with the CTRIO? I have done this in the past with the High speed counter inputs at X0 - X3 on the DL05 pretty well. But I have to use them to count another pulse count from a different device.
Created Date: June 02,2004
Created by: elevmike
It seems to me that you'll have to do a ADDD K600 to the current encoder count, and store that in two consecutive mem locations for a compare (CMPD) to counter. When the compare is true (SP61=on), stop the feed, cut, ADDD K600 to V-Target, start feed and CMPD V-target to counter etc...
Created Date: June 02,2004
Created by: laveryt
The feed can't be stopped for any reason. The CTRIO unit operates as its own Controller so to speak. It works somewhat independent of the PLC.
Created Date: June 02,2004
Created by: elevmike
If the feed never stops for the cut, then I would suppose that the cutting device would jamb the feed material??
Question: How does the cutter work? Is it a sheer, rotary cutter, or saw?
If your using a DL06, X0, & X1 can be used for your encoder inputs up to 5kz rate. (unless your using an AC input model). What's the expected count rate?
I'm having a hard time imagining your process from the description you gave.
Mike.
Created Date: June 02,2004
Created by: bcarlton
I'm jumping in before laveryt replies with my guess. Most cutoffs of this type have the cutting mechanism moving at the same rate (mechanically coupled ?) as the material in the direction of its feed. Once the cut is complete the cutter returns to a home position at high speed.
Created Date: June 02,2004
Created by: elevmike
I checked out laveryt's website. It appears that he's cutting plastic tubing. I'll buy the moving cutter idea. I would still use the same process as I described above, but eliminate the stopping component.
I get from your 1st post that the expected count rate is 120 hz. It seems you should 'nt need the H0-CTRO for this application.
Created Date: June 07,2004
Created by: laveryt
Inputs X0-X2 are being used to count another High speed input pulse. The cutter is a rotating knife. the feed does travel with the product flow as was suggested.
The reason I wanted to use the CTRIO was because it responds faster than the PLC's logic would. At speeds of 120 Cuts per minute a few milliseconsd adds up to cut errors. we cut product all the time with +/- .005 inch requirements which doesn't leave much time for scan time lag.
Created Date: June 07,2004
Created by: elevmike
If your using a 12 " circumference wheel on your 600 PPM encoder, you cant expect accuracy of more than .020 inches. 12 "/600ppr=.020 in.
You will need a 2400ppr encoder to achieve the desired accuracy.
Created Date: June 07,2004
Created by: laveryt
in Quadrature its .005
Created Date: June 07,2004
Created by: elevmike
I dont get it. If the count for 12 inches is 600 then how do you get a count for every .005 from thoes two values??
Hey, why not put a blade on a 12 " cir wheel that is geared to the feed?