reading from a CF during Powerup

[sunnyvaleplc]

Hello everyone,

I am reading and writing to a compact flash in the compactlogix L32E controller. I wanted to know, how can I read from the compact flash JUST ONCE during the Power up only.

I need this, to re-instate the tag values that were changed before power cycle.

I have tried the S:FS and the power-up handler and both doesn't seem to work. I can read from the CF during normal operation, so I know the reading part is definetly working.

How do I just read only once after a power cycle ?

Thanks,

sunnyvaleplc

 

[kamenges]

I'm guessing that the PLC isn't quite ready to read from the CF card when you are trying to.

Latch a bit on the first scan of the processor. Don't allow normal read/write access any time the bit is set. Perform a separate read to determine only if any reads are successful (I assume that an unsuccessful read will throw an error). Once you get a successful read, trigger the restore read from the CF card. When that read completes, reset the latched bit and allow normal reads and writes to continue.

Keith