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Xinje PLC Labeling Machine Servo Conversion
Client · Textile labeling line · motion control retrofit
Challenge
A textile labeling line ran its pull-strap motion on encoder feedback. The encoder mounting was a recurring mechanical failure point, and the closed loop was hard to tune and maintain. The plant wanted to move to a pure servo solution — but nobody had audited the existing ladder logic end to end, so the risk of breaking undocumented behavior was real.
Approach
The retrofit was prepared in three parts: a full ladder-logic state-machine audit that mapped every branch and identified dead code, a mechanical simplification from encoder closed loop to pure servo open loop, and a customer modification document the on-site team could execute without the original developer.
Dead code branches were documented rather than silently removed — changing them stays the customer’s call. The document specifies the exact rungs to touch, what to test after each change, and the expected behavior of the new servo timing.
Stack
Results
- ✓ Eliminated encoder feedback dependency, reducing mechanical complexity
- ✓ Full ladder logic audit: identified and documented dead code branches
- ✓ Delivered customer modification document for on-site engineering team
Takeaway
A motion-control retrofit is only safe when the existing logic is fully mapped first. The document was the real deliverable — the code change was small, the confidence came from the audit.