Can any one tell me the most perfect way of implementing totalizers in Allen Bradley PLC's.
I am using PLC5/80E with RS Logix5.

 

There are two pretty good ways.

Method 1 uses an STI program to get the flow at a regular time inteval, and calculate the total based on the rate times STI time interval.

Method 2 uses the Last Scan Time (S:8) and multiplies it by the last BTR'ed flow rate.

Method 1 is arguably more accurate, if the STI time is small enough. Method 2 doesn't take up the one STI (which may be needed for PID blocks), and calculates as fast as the PLC scan time.

 

Hello:

I am replying to your "totalizer" posting:

I have developed many algorithms for this using ladder logic (proprietary non-AB/Rockwell) software however, I have used RS-Logix 500 and I believe that I can offer some assistance.

Reply to this email if you are interested.

Regards,

Rick ([email protected])

 

For flow totalization I use Last overall scan rate (S:8) as the time base to calculate flow every scan and add to the same register. I have found this to be much better then using PLC timer and very accurate.Let me know if you need further details.
Herman Bilalyan
Principal Engineer
Teknor Apex Co.

 

Dear Herman,
Do you have a sample you could send me?
Regards,
Gabriel