adccommunitymod (AutomationDirect) asked a question.
Created Date: September 11,2010
Created By: Kristjan H
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Several of my D4-450 behave like this: when I write an updated program to PLC in run mode the input registers on F4-08RTD reset to zero and then return to normal. This causes problems because it triggers frost protection in the system (temperature below limit sets C-bit) and I need to reset the frost protection after each write. Why does this happen? Shouldn't the registers maintain their value through write? What can I do to prevent the false triggering? I am using the method from page 9-14 in the F4-450 manual. I have tried using SP0 but run-time edit doesn't equal power-up or program-to-run transition. What else can I try?
Created Date: September 23,2010
Created by: Kristjan H
:confused:
I don't believe that no one else has experienced this... Has no one seen inputs on F4-08RTD go to zero on write-to-plc?
Created Date: September 23,2010
Created by: JoeW
Have you thought about changing your logic so that a value of 0 in the input register has to be read for a certain amount of time before the frost protection triggers?
Created Date: September 24,2010
Created by: Kristjan H
:)
Thanks Joe, this simple solution does the job and it actually only occurred to me yesterday! I have been trying to solve the wrong problem for a long time :o
Created Date: September 11,2010
Created by: Kristjan H
Several of my D4-450 behave like this: when I write an updated program to PLC in run mode the input registers on F4-08RTD reset to zero and then return to normal. This causes problems because it triggers frost protection in the system (temperature below limit sets C-bit) and I need to reset the frost protection after each write.
Why does this happen? Shouldn't the registers maintain their value through write? What can I do to prevent the false triggering? I am using the method from page 9-14 in the F4-450 manual. I have tried using SP0 but run-time edit doesn't equal power-up or program-to-run transition. What else can I try?