Trying to count

I AM USING A DL05 PLC, WITH 3 INPUTS (PHOTO EYES), THAT ARE COUNTING BOTTLES ON A CONVEYOR LINE. NOT HAVING DOUBLE COUNT ISSUES, BUT THRU THE SHIFT COUNTERS WILL BE OFF LIKE I'M MISSING COUNTS. SEEM TO BE GETTING MY INPUTS EVERY TIME, COULD I BE USING THE WRONG PLC? ALSO JUST USING SIMPLE PROGRAMMING, INPUTS FIRING COUNTERS THEN STORING FINAL COUNT AT END OF EVERY SHIFT.

WOODMAN1

Zip and post your program. How fast are the bottle moving past? How long would the PE be on, how long off between bottles? Check your scan time. Both the ON and the OFF times must be longer than the scan time. Also, what type DL05?

View attachment 208_BOTTLE.zip
I am using a D0-05DR. Right now I have a 3ms scan time, I have tried increasing my scan time but it makes getting counts every time worse, than with a smaller value. Bottles are moving at a high rate of speed about 8000 bottles per hour.

I have tried increasing my scan time but it makes getting counts every time worse,...

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Woodman, yes, and decreasing your scan time should result in fewer missed counts. If counts are still missed with the shortest scan time, then you may need to use a High-Speed Counter (HSC instruction) instead of the UDC. You need a High Speed Counter Module in order to use the HSC counter. Check to see which Automation Direct PLCs will accept the High Speed Counter Module. I am almost sure that the D0-05 does not have provision for that module.

I agree with bernie, the speed of the bottle past the sensor might be the determining factor, along with the sensor response time. 8000 bottles per hour equals .45 seconds per bottle (or 450 milliseconds per bottle). Your sensor response time just might be the problem.

The high speed module for the DL 05 is the H0-CTRIO

If the 450 ms per bottle were 275 ms on and 275 ms off then it should work, but we need the actual ON and OFF times of the inputs. The ON times may be very short.

bernie_carlton said:

If the 450 ms per bottle were 275 ms on and 275 ms off then it should work, but we need the actual ON and OFF times of the inputs. The ON times may be very short.

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Along the same lines Bernie is thinking. Please indicate the input condition state (on or off) when a bottle passes the photo eye.

If the inputs are too fast for normal ladder counters the DL05 supports one high speed counter and the CTRIO can provide two more counters.

Woodman1,

Looking at your logic I see one problem not related to counting, but to the reset of the counts. The DL05 does not have a real timeclock, so the use of V7770 and V7767 will not give you useable results.

Back to the counting issue. Presuming that all your inputs have the same common. One test if the length of signal on time (pulse catch) is the problem is to put a value of 50 (BCD) into V7633 and a value of 5 (BCD) into V7634. This will setup X0 as a pulse catch input. With this configuration if X0 turns on during any time during one PLC scan it will place a 1 in the address. If the input was configured as a normal input it would only report 1 if it were on (and if filter conditions were met) at the moment the PLC transferred the status of the input table.

Now disconnect all but one of the photo eyes from the inputs and place jumpers to the disconnected inputs so that only one of the photo eyes fires the programmed inputs. Run bottles for a day and note any differences in count. Do this for each photo eye until you discover if one of the signals is the one with the short pulse.

The bad news is that only one of the inputs (X0) can be configured for "pulse catch".

You have indicated that your application is bottle counting. You have also indicated that the signals you are receiving are good. I would encourage you to double check this. The classic photo eye to use for bottle counting is a polarized retro reflective eye. The problem occurs when using one that does not have the ability to offer NC or NO outputs. The pulse catch will not work on a fast moving bottle if the photo eye turns on the input when it "sees" the reflector.

I totally missed the timeclock aspect. If he is using the Memory Cartridge then he will have these but then it throws out using the CTRIO. Maybe a better application for a DL06, maybe use interrupts.

Thanks for all the info, and yes I am using the memory cartridge for date and time. I reset my counter values at the same time the blow machine resets its counter values. I haven't actually gotten the time on or off of the PE, but the on state is very short,and PE is on when it passes the eye. I think I will need to upgrade to DL06 to get the use of high speed counters.

What kind of sensors are you using, photo eyes cover a huge spectrum of sensors... where and how are they positioned ? Are they clear bottles you are looking at ?

JV

I am using a SICK fork sensor WF80-60B410.Yes they are clear bottles. I have also used a retro reflective Allen-Bradley PE, with same issues, I chose the SICK PE, as they were being used on some of our molding machines for counting purposes.

Sensor should be ok and is quick enough, the only thing that concerns me is the position.. I would try and position it so it is,nt looking through clear glass per say but maybe at the neck of the bottle or a contoured surface.. I had a issue like this before, one of the problems was the sensor was seeing straight through the bottle at times !! I also found the reponse time was increased dependant upon the location of the sensor relevant to the plc...

Just a couple of thoughts...

JV