Siemens · SINAMICS G120
A STOP A request has been initiated, often due to a safety-related event such as defective hardware, incorrect STO configuration, or a discrepancy at STO terminals. This condition is indicated by fault value r0949 and results in an immediate, uncontrolled cessation of motor power. It is a critical fault impacting machine safety and operation.
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Measure the voltage across STO input terminals (e.g., X124/1 and X124/2 for F-DI1, X124/3 and X124/4 for F-DI2) with a multimeter to verify an active "1" signal (24VDC) when STO is not active.
Verify the integrity of all external safety components in the STO circuit (e.g., E-stop buttons, safety light curtains) by actuating them and observing their electrical state.
Check the parameter P9501 (Safety Integrated function selection) to ensure STO is correctly enabled or disabled according to the system's safety concept.
Inspect the wiring for the STO input channels (e.g., terminals X124/1 through X124/4) for loose connections, insulation damage, or short circuits.
Execute a safety function test (e.g., using P9700=1 to reset) after verifying external safety circuit integrity and parameter settings.