step 7 micro win programming

[suchitradevi79]

hi friends
For one of my project i am using siemens PLC. cpu 224
I have 16 analog inputs. just have to monitor and give the alarm if the level exceeds 20%. 4-20mA current input to the analog slot channels.
can i use the S_ITR instruction for all these?
please advice.

thanks
chitra

 

[BryanG]

For those like me who had never seen the S_ITR instruction it is part of a 'Scale' library that you can download from the Siemens website. What happened to the day when you did a I to DI, DI to Real and then wrote your own scale function!!
http://support.automation.siemens.c...csview&extranet=standard&viewreg=WW#A27196050

In answer to chitra:
The S_ITR instruction converts the Integer from the analog input to Real and then scales the Real to get an output. It won't give an alarm, you could use a compare instruction for that, unless Siemens have also given a 'alarm' function to download.

 

[adfox]

I'd write my own function to scale and detect limits and call it 16 times with different parameters.