PLC-function Block Programing

[garyg2006]

Just started using Crouzet PLC function block programming. I have the basics but I am having trouble writing a step that uses a 4-20mA signal (ultrasonic tank level sensor)and calls via modem when the level drops below a fixed level after it begins to fill. This would only happen due to evaporation or a leak. The process is a batch process so the tank should never decrease in level until it is processed by the operator.
thanks to anyone that can help.

 

[MikeHalloran]

Be careful about your own assumptions.
The phrase "should never" should never appear in your documentation of the software.

E.g., when a tank fill valve opens, it is possible for the incoming flow to disturb the surface in such a way that the level seen by a transducer will go down, as in a standing wave.



Mike Halloran
Pembroke Pines, FL, USA

 

[garyg2006]

Thanks for the tip but we have the sensor isolated with a standpipe and have been using it for 6 years without any problem. My concern is more about evaporation and level loss since we are now processing a different fluid. I'm more interested in help with sequence of the function blocks to write the program.

 

[IRstuff]

If you really want some help, you should post the code that you have, and maybe someone can guide your work.

TTFN

FAQ731-376

 

[garyg2006]

Good Idea. I saved and attached the program file as a PDF. The analog input at the bottom of the logic page is the tank level sensor. I want an alarm message (such as input 2) if the level drops while the tank is filling over a 1 week period of time.

 

[MiketheEngineer]

You might also check out Tek-tips - a sister site to this one that specializes in programming - and I think PLC

 

[IRstuff]

No, the PLC forum is here: forum791

TTFN

FAQ731-376

 

[garyg2006]

thanks,
I'll check it out.