Siemens 545 (Simatic 505 Family) Help - How to program a simple totalizer??

[alcurtis]

So, I have a Siemens model 545 (TI) PLC. I need to program a simple totalizer but cannot find any reference material to get me started and Tech Support is having difficulty finding a resolution. Is it that hard?? Can anyone help me? Analog IN WX is 4-20 ma, 0-100 GPM.Is there a simple calculation ie: SFPGM, Scaling Block ect?

 

[HLeap]

It depends on how accurate you need to be. A simple piece of Logic with a one second timer and a calculation block. Once a second you would perform the following calculation:

X = X + (Y/60)

Where:

X = Flow Total in Gallons (Floating Point)
Y = Current Flow Rate reading from your Analog in GPM (Floating Point)

You would probably want to pick a reasonable rollover point and
write a piece of logic for the following:

If X > 999,999 then X = (X - 1,000,000)

Assuming the rollover point you pick is 1,000,000.

 

[alcurtis]

Thanks a bunch HLeap. I figured it was simple calc but needed some help to get started. I don't think the total will ever reach 1,000,000 on a monthly schedule so rollover is probably not needed. Based on the PLC clock for 30 days, I'll simply move the value to a register for "previous month total" and then reset for "current month total" to start new totalization.

Thanks again.