Plant Engineer

Hello everyone. I am trying to progam RLL to take encoder data and compare a change in the count to allow for another action in my program. What i have is a working encoder that im reading the count into a register the count starts off with a trigger from a prox then i zero the count at the trailing edge of the prox signal. I am looking for a change in lenght of the pruduct passing by. I have tried to use the PLC scan time to detect this change from one size to the other. I cannot seem to make it work. All i want is to detect a change in lenght of the product passing threw the process to track the count of products at defferent lenghts. Any sugestion would be great.

Thanks

please provide the name and model of the plc and the name and model of the encoder.

regards,
james

Before you zero the encoder move you count into a storage register.

If prox true count then when prox false one shot register value to Storage Register then zero Register Value. This way you should always have last Count in Storage Register.

If I understand correctly you have a single prox that is held true while the product is passing? If so:

On Rising edge of prox store current encoder count into Count_Start_Value

On Falling edge of prox store current encoder count into Count_End_Value

Length of Part = (Count_Start_Value - Count_End_Value)

Multiply by UnitsofMeasure per Count to get in Engineering Units

That's it in simplistic terms. Things you should also account for:

Debounce the prox signal with a timer if there's a chance it can flicker on/off during part traverse

Account for rollover of your encoder...At some point it's going to rollover 0

Plant engineer

The PLC model is a direct logic DL06. Im using direct logic software ver. 5.3.194. The encoder is a generic automation direct type at 1200 CPR. View attachment Ladder View.pdf
Attached is the section i am working on the encoder inputs to the UDC and v7000 7001 are the registers im using.

Thanks

Sorry try this attachment

View attachment Ladder View.pdf

Regards

OR on PLC side,

Sequence,

1.) object detect.(through beam sensor)
2.) Postive edge Triggering.
3.) reset counter(1 pulse)
4.) count start.
5.) object end.
6.) count stop.(display length measurement)
7.) loop back.

e.g in plc program-> 250 count*scale unit(real value/floating)=length.

osmanmomin said:

OR on PLC side,

Sequence,

1.) object detect.(through beam sensor)
2.) Postive edge Triggering.
3.) reset counter(1 pulse)
4.) count start.
5.) object end.
6.) count stop.(display length measurement)
7.) loop back.

e.g in plc program-> 250 count*scale unit(real value/floating)=length.

Click to expand...

Other than I'm not sure the OP has a pulse generator so no need for a counter. Just record the beginning and end values of the encoder and subtract.

OP...You say you have a 1200 PPR encoder. Are you connecting the Encoder to read a PULSE or the value from the ENCODER? Makes a difference on how you plan to operate. In other words how is the encoder connected? If you are connected to just a digital input, at 1200 PPR, how fast is the encoder spinning, because you could also be missing counts.