Troubleshoot Excessive CEMAT Drive Startup Warning Time
For an unexpectedly long CEMAT drive startup warning, inspect the affected block's documented calling OB before changing its warning duration. An OB1-related change reportedly resolved this case. Siemens' CEMAT V7.1 reference specifies OB1 for C_DRV_1D, but specifies a time OB for C_PID3. The appropriate correction therefore depends on the exact block and release; putting every CEMAT block into OB1 is not a valid general instruction.
Table of Contents
- Confirm the Actual Block and Release
- Documented Calling-OB Requirements
- Review and Correct the Runtime Assignment
- Keep Controller Scheduling Separate
- Verification
- Limitations and Operational Precautions
- Engineer FAQ
- Technical References
- Related Articles
- Related Tags
Confirm the Actual Block and Release
A drive's configured one-second warning was reported to last about twenty seconds or longer before motor starting. Moving the relevant CEMAT execution to OB1 reportedly resolved the delay. The exact CEMAT release and drive-block variant were not identified.
Do not treat those reported durations as measured timing performance. Record the installed block name and version, warning parameter and current runtime assignment before changing the program.
Documented Calling-OB Requirements
The opened CEMAT V7.1 Objects reference specifies OB1 (MAIN_TASK) for C_DRV_1D. Its C_PID3 controller chapter instead specifies a time OB, for example OB35.
This demonstrates why a blanket instruction to put every CEMAT block in OB1 is unsafe as a general rule. The affected installation's exact-version requirements still need confirmation.
Review and Correct the Runtime Assignment
Use this engineering procedure, with the exact release documentation controlling the final assignment:
- Preserve the AS project and master library.
- Identify the affected drive instance and trace its CFC runtime assignment.
- Compare that assignment with the installed drive block's documented calling-OB requirement.
- Review related CEMAT blocks and their documented sequence requirements before moving a runtime group.
- If a mismatch is demonstrated, prepare the corresponding assignment correction in a project copy.
- Compile and review the proposed download consequences before deploying under an approved operating condition.
The observed recovery supports investigating the calling context. It does not establish an internal timer mechanism or a numerical scaling factor that can be applied to other projects.
Keep Controller Scheduling Separate
If the chart also contains PID functions, identify each actual controller block before choosing its task. The documented C_PID3 example requires a time OB; it should not be moved into OB1 merely to match a drive.
Review the controller's execution interval and associated parameterization using its own release documentation. No universal OB35 cycle, smoothness improvement or performance result is established here.
Verification
Under approved conditions, record the start command, warning indication and motor feedback using a common observation method. Compare the elapsed sequence with the configured requirement and the intended group or single-start behavior.
Confirm that related sequencing and controller execution remain correct after a runtime-assignment change. Retain the original assignment and test observations. A compile without errors does not demonstrate the physical startup sequence.
Limitations and Operational Precautions
The exact drive variant, CEMAT release and required runtime dependencies are unavailable. Therefore the V7.1 calling-OB rules are a bounded manufacturer baseline, not proof for every CEMAT generation.
The separate request to enable OS_Perm.bit31 cannot be resolved from this information. The opened V7.1 reference does not establish that parameter mapping. Do not apply an APL permission-bit interpretation or modify a permission word without the exact block's definition.
Preserve interlocks and startup warnings during investigation. Review actuator availability and rollback before downloading a scheduling change.
Engineer FAQ
Was moving the drive to OB1 reported to help?
Yes, for this configuration; that is a reported resolution rather than a universal test result.
Must all CEMAT PID blocks go into OB1?
No. The opened C_PID3 documentation specifies a time OB.
Can OS_Perm.bit31 be enabled from a generic example?
Its exact meaning and implementation remain unverified here.
Technical References
- Siemens: CEMAT V7.1 Objects Reference Manual, March 2011 — C_DRV_1D chapter, Calling OBs, chapter page 4 (PDF page 23); C_PID3 chapter, Calling OBs, chapter page 4 (PDF page 539).