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Pa1990

Saving Tag Values to SD card of AB processors

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Hi All,

I have a quick question, in regards to the new logix processors that have SD cards, I have seen the option to save/load a plc program from the SD card. However is it possible to save certain tag values to the SD card and load back again in the case of a power fail or download? if so would you have an example of code that saves two tag values to an SD card and and loads back out again?

Certain values like positioner's,timers & calibration values need to be saved but not hard coded. But in the case of a power fail or re download etc this can be lost. so if we could select tags to be saved into the SD card, and if needed be loaded back into the PLC.

Any sample code, or info would be appriaciated

Thanks

Edited by Pa1990

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It's not as simple as checking a "retentive to SD" box for the tag and having it auto-loaded when you reboot.

But you can write logic that saves tag data to the removable media, and reads it back out.

This logic has a rocky history from back in v16 with CompactFlash cards (about 10 years ago) but it's pretty solid now, especially because modern controllers use SD cards, which have data integrity features built in.

There's a Application Profile manual for this feature:

http://literature.rockwellautomation.com/idc/groups/literature/documents/ap/logix-ap007_-en-p.pdf

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