PLC Programming - Implementing Totalizers


Thread Starter

Alok Khatlawala

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.


Allen Nelson

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.


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.


Rick ([email protected])


Herman Bilalyan

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.