Project from PLC with different version of CODESYS

CODESYS
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I am attempting to load a project into CODESYS from the PLC (EPIC). This is a new customer for my company and we don’t have the original code, but we are able to get the source off the PLC. However, I get the following message:

Screenshot 2026-08-25 163845
Screenshot 2026-08-25 163845557×360 10.1 KB

I have several different versions of CODESYS installed: SP20, patch 4; SP20 patch 6; and SP1 patch 1. I am trying to load the PLC program and log in to the PLC without making any changes. What is the next thing I should do? Should I try to get SP 20 with no patch installed? Should this be fine on SP20 patch 6?

Thanks in advance!

-Caleb

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Solution: Download originally used version of CODESYS onto the computer and install. You may need to update / find some older libraries as well. I was able to get logged into the PLC this way.

While that worked for my first PLC, I have a second one where it looks like I need the Opto22 library, but an older version then what is immediately available in the downloads section. Does anyone know where I could find this? I need version 3.1.2.0 not 3.1.3.0.

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