AB1756 Questions

I have to buy a spare 1756-L62. Are the series A and B interchangeable? Can I update the firmware on a Series A to series B and vice-versa?

Thanks

In general, the 1756-L6x controllers Series A and B are interchangeable.

Series B has a different battery (blue shrink wrap with different performance), and the location of the CF card slot was moved to the front instead of the bottom.

Series B uses the battery and nonvolatile memory differently, and you can't mix Series A and B in a Redundancy pair. The firmware for early revisions of v12 and v13 didn't support the Series B hardware, but v15 and up has supported both from the start.

If you want to get into the details, I recommend RA Knowledgebase Articles:

32357 Observations of Nonvolatile Memory in L6X Logix Controllers Series A and B (TechConnect Required)
43312 1756-L6x Controllers: Difference Between Series A and Series B (TechConnect Required)

But in general if you have a typical v15, v16, v17, v18, v19, or v20 Logix program in a non-redundant controller and you need a backup CPU, you can use either Series A or Series B.

Do you know on what chip Firmware is stored.
I have problem with my ControlLogix I/O card, 1756-OA16 has one flash memory. Is it possible that firmware has been stored in this location?