Parts count

I have a EOAT that will be picking 16 pieces. There are sensors for testing part quality on the tool so at times some will be rejected. The good parts will then be dropped in a box and I need to keep track of the count. Does anyone know of a good way to count parts while they are still on the tool after the quality test. Hope I have explained this well enough. Thanks in advance.

Bill

I assume that your EOAT is a robot? If so, is it connected to a programmable controller? If so, then use a counter in the PLC to count the number of parts that passed the robot part quality test.

Yes it is a robot and I will be connecting it to a PLC. The problem is I will only have a signal if the part is bad and they will all turn on at the same time or at least close enough that if there is more then one bad part than I can't assume each will trigger the counter separately for an accurate count. After thinking about it the only thing I have come up with is copying the input states to a shift register and clocking them out using one of the empty word bits as a counter input. The just subtract the bad parts from the total for the good part count. Sorry, I didn't explain it well in the original post.

Also the input state will not change until I drop the parts.

Yes it is a robot and I will be connecting it to a PLC. The problem is I will only have a signal if the part is bad and they will all turn on at the same time or at least close enough that if there is more then one bad part than I can't assume each will trigger the counter separately for an accurate count.

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You mean that you can have an individual PLC input for EACH bad part? If so, just set up 16 memory locations and if a specific part (say # 8 out of 16), then the bit for the #8 memory location goes ON. Then count the total number of memory locations #1 to #16 that is ON (bad), and handle each bad part as required (reject).

This is a very common procedure and should not present very much of a problem using a programmable logic controller. A PLC can handle many things in a short time period - 1 PLC scan (so short that it appears that all 16 are being processed at once but in reality the PLC does each sequentially one after another).

Typically, this is done in robot code. At a position or during a range of positions, the sensors are checked, and the count can be calculated there, pick zones turned off (to drop rejected parts), and to update the destination data field representing its contents.

This data (contents of the destination bin/pallet) can be exchanged with the PLC, but let the robot program dictate the exact position and timing range during which you want a "snap shot" of the gripped part quality/presence, and do the counting there.