This article aims to provide insight into a recurring issue with Rockwell Automation’s Studio 5000 programming software (v24), specifically an anomaly that affects built-in base instructions such as XIC, XIO, and OTE, rendering them as UNKNOWN (UNK) in the logic editor.
Despite Rockwell Automation’s claims of having resolved this issue in previous versions, this problem persists, as evidenced by a related Rockwell Technote: 866333.
This technote addresses a similar issue that was reportedly corrected in version 24, yet the anomaly continues to manifest in version 29. This article will delve into the specifics of how this error presents itself and the steps taken to resolve it.
Problem
Certain relay instructions (such as XIC, XIO, OTE) come up as unknown instruction error UNK after an upload in Studio 5000 v24 and v29.
Cause
The issue arises when public parameters are linked to different bits within the same program-scoped tag. The problem is triggered by two factors: firstly, the parameters are public, and secondly, they are aliased to the same program-scoped tag, differing only in bit position. For example:
Workaround
For the below example, the program will function without error (will not show UNK instructions on upload):
- ppa aliased to controllerScopedDint.1 (where ppa is the a public parameter and it is aliased to controller scoped tag controllerScopedDint.1)
- ppb aliased to controllerScopedDint.2 (where ppb is the a public parameter and it is aliased to controller scoped tag controllerScopedDint.2)
Solution
This issue was identified in Studio 5000 v24.00 and has been resolved when upgrading to higher versions such as v24.02 or v29.00.
Another similar issue, which involves UNK instructions due to program corruption but not related to public parameters, is detailed in 515409 – XIC instruction doesn’t work correctly in RSLogix 5000 software.
Frequently Asked Questions
What is the meaning of an “unknown instruction error” in Studio 5000?
An “unknown instruction error” in Studio 5000 typically indicates that certain instructions, such as XIC, XIO, or OTE, are not recognized by the logic editor, showing up as UNKNOWN (UNK). This can occur due to issues like program corruption or incorrect parameter settings.
How do I determine the cause of an “unknown instruction error”?
To determine the cause, check if public parameters are linked to the same program-scoped tag but differ in bit position. Also, investigate any potential program corruption or compatibility issues between different versions of Studio 5000.
Is there a permanent fix for the unknown instruction error in Studio 5000?
Yes, Rockwell Automation has addressed this issue in versions v24.02 and 29. If you’re experiencing this error, ensure your software is updated to these versions or later.
Can I prevent unknown instruction errors from occurring?
To prevent unknown instruction errors, avoid linking public parameters to the same program-scoped tag with different bit positions. Regularly update your software to the latest version to benefit from fixes and improvements.
What should I do if updating doesn’t resolve the error?
If updating doesn’t resolve the error, consult Rockwell Automation’s support resources, such as technotes and forums, for additional troubleshooting steps or contact their customer support for assistance.