Shift register Bit length of the shift data set from HMI

4 posts in this topic


I have a project and intended to use a FX3U PLC and E1071 HMI with a 1000ppr encoder.

The project involves scan an object placed inside a blister cavity and decide it is good or bad by a sensor. If the object is good, then the input X007 turns ON and if the object is bad, then sensor doesn't activate X007. The blister is created in a PVC film roll and is in continuous process. A knife cuts the pack as per the size required, then the pack will move to a reject/accept station. The physical length from scan station to knife station is fixed

If I use SFTLP, I can track the X007 bit until it reach the reject station and take the decision to reject or accept the object.

But the issue is the number of packs from scan station to Knife station will vary according to the size of the pack. Bigger pack size has less 'Bit length of the shift data' (The length of shift register, n1) and smaller pack size have large 'Bit length of the shift data'.

It is required to set the 'Bit length of the shift data' from the HMI, but the 'n1' of the FNC 35, SFTLP cannot take a D Register to set the value from HMI and it is a constant K or H.

I have seen the operation on other machines using HMI to set the length of the Shift Register. but I cannot figure out the logic behind it.

Could anybody please help?

Thank you for your time.

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Do you have many different pack sizes ?
If it's only a couple why not just set up a  SFTLP for each pack size?

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Thank you Gambit for your reply.

The pack sizes wont be in a comfortable range to add lines for every pack size. But if there are no other options then, will go that road.

I was considering that option, but as I always do things in a hard way, I thought I am missing a simply logic for this problem.

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your problem would be i guess that you check the bitlength for any 0 right to determine if the strip is ok.?

So why not have a longer bitlength for all type and just add the 1 needed (depending on the size) by using WOR instruction for instance for.

The WOR value can than be entered in the HMI.

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