Using the clock pulse signal to count up accurately in FB

Hi 

I'm having difficulty using the clock pulse signal to count up accurately in my FB !! 

Not sure if I've missed something... but would appreciate any help before i lose my mind :) 

The problem is the count is incrementing way more pulses than the frequency should provide in a set period. 

i.e in 10 seconds using 10Hz i should have a count of 100 ? but i get a variation over 800 !!

When I use the 1HZ bit there doesn't seem to be a problem !

PLC Cycle time 7ms ( range 4ms to 29ms)  

I have;

Clock pulse bit (M0.0 -10Hz) declared as input #SpdPls

#SpdPlsM = STAT

#CycCnt = STAT

A(

A #SpdPls

BLD 100

FP #SpdPlsM

)

JNB _001

L 1.000000e+000

L #CycCnt

+R

T ~CycCnt

_001:NOP 0

 Any Help would be appreciated 

Thanks 

------------------------------------------------------------------------------------------
Split from Clock pulse in Step 7-s300.

Hi!

I have tried your code in PLCSIM, but it works perfectly OK, also with 10 Hz!

Check the use of M0.0 in other parts of program....

BR!

uel123.

uel123

Hi!

I have tried your code in PLCSIM, but it works perfectly OK, also with 10 Hz!

Check the use of M0.0 in other parts of program....

BR!

uel123.

 HI

Thanks for looking into this..

It's definitely not working in the plc, I've tried investigating using many variable and found its the declared inputs which appear to be providing the issue ! 

When I use the glabal M0.0 10Hz within my FB its fine however when i use this as an input to the block my problem returns.

It seems the same if I'm trying to use edge detection from a local input. 

I've tried calling this FB block in OB as apposed to my FC but still the same..

Its driving me crazy i will check the use of M0.0 elsewhere but seems ok within FB 

Thanks