ftview se derived tag a=a+b

hi, i am new of scada world,

when i build 2 analog tags named "add" and "total", set total = 0, add = 1,and write an expression

tag name: total

if system\Second == 1
then total + add
else total

into derived tag, then display it, when second equal 1, total become to 1, and start blink 0 1 0 1 0 1, is there anything wrong with my setup?

if system\Second == 1
then total = total + add
else total

You have not changed the total.

Regards,

You shouldn't have to use the "If" statement with system\Second.
Do you just want to update every 1 minute?

With the derived tag file open, set the update rate to 60 seconds:
from the menu bar Setup>Derived Tag Setup

Then your expression can be:
total + add

DukeNeo said:

hi, i am new of scada world,

when i build 2 analog tags named "add" and "total", set total = 0, add = 1,and write an expression

tag name: total

if system\Second == 1
then total + add
else total

into derived tag, then display it, when second equal 1, total become to 1, and start blink 0 1 0 1 0 1, is there anything wrong with my setup?

Click to expand...

Your then clause evaluates to 1 (0+1)
Your Else clause evaluates to 0
You should see a "0" for 59 seconds, then "1" for 1 second cycle.

You really don't need an Else clause at all. As others have said, you want to display "total" and execute total = total + add once a minute. Be aware, your If system\second == 1 may not execute just once every minute. If you can't trigger it differently, you will need a little extra code to ensure it only updates once when system\second ==1.