STO - Safety Torque OFF / Sorter Start Prevention (Silent Interlock Fault)
The AFE1 tray sorter merge stops intermittently or refuses to start. No explicit "E-STOP Active" or "VFD Fault" text alarms appear on the hardware keypad or the main HMI diagnostics, creating a "silent lock" on the transportation startup sequence.
Environment
- VFD Target Node: EATON PowerXL DG1 (Model:
DG1-342D2FB-C21C) designated as conveyor drive VFD45395 (PROFIBUS Node 09)
- Safety Hardware Interconnection: Intellimerge VFD Board Interface Box (IBX45005-2) handling hardware E-STOP loops
Answer / Solution
The Safe Torque Off (STO) condition occurs when the drive's dual-channel safety circuit opens.
When a PROFIBUS communication option card (Slot A) freezes or fails logically, it stops updating its output words to ICW
Test
- Replace the PROFIBUS Communication Card: If the drive keypad stays healthy but jumping the safety circuit loops does not establish a persistent online state in the PLC network configuration, replace the option network interface module inside Slot A of the Eaton DG1 controller.
- Cycle System Control Mode: After inserting the new card, toggle the VFD control destination into manual mode via the keypad interface, then switch it back to remote. This forces the network parameters to re-initialize and sync cleanly with the ICW server.
Related items
(KB-12546)
Internal Notes
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