It is firmware. If its code that is stored on a chip, its firmware. But the exception is that it is “independently upgradeable code” that is most likely custom code. Another issue is that it DIRECTLY effects or controls a GxP process. So it is validated as part of the system.
You may also be able to pre-program and validate an identical PLC and have it on the shelf as a hot spare. Since it was installed and validated in the system it is intended to function in. It can be considered a like for like replacement, and re-validation of the system should not be required. In fact, you should not even have to do a formal change control. Noteing it in the log book should be good enough.
However, when the broken PLC comes back and gets re-coded, techincally it should be re-vaildated. Another thought is that you may consider it like for like and justify not revalidating it by conducting performance monitoring on the system after the repaired hot spare is installed.
Automated process is ANY process that is not COMPLETELY performed by a person. If the code in firmware enables a person to skip having to do certain steps in a process, then it is an automated process. The test is to remove the firmware and if you can still complete the process using exactly the same steps used when the firmware is in place and get the exact same result(unlikely), then it is not an automated process because the code is not involved.
Just some thoughts, comments?