231-6100

Check External Safety Devices

Verify all E-stop buttons are released, safety doors are closed, and light curtains are clear. Check safety relay status in PLC diagnostics.

Do not bypass safety devices - resolve the actual safety condition first

Inspect Safety Circuit Wiring

Check 24V safety circuit continuity from safety relays to drive STO inputs. Measure voltage at drive terminals X3/1 and X3/2 (STO+ and STO-).

STO circuit should show 24V when active - 0V indicates safety circuit interruption

Reset Safety System

After clearing safety conditions, reset the safety system and acknowledge alarm using ALARM key, then press CE to clear the message.

Some systems require specific reset sequence - check machine manual for proper safety reset procedure

Check Drive Status LEDs

Examine servo drive front panel LEDs for fault indicators. Red LED typically indicates drive fault with STO activation.

Heidenhain drives show specific LED patterns - consult drive manual for LED diagnostic codes

Access Drive Diagnostics

Navigate to MOD function, select drive diagnostics, and check drive internal fault memory for overcurrent, thermal, or communication errors.

Drive fault codes are stored even after power cycle - check historical fault buffer

Verify Drive Parameters

Check drive configuration parameters match motor specifications, particularly current limits and thermal monitoring settings in drive setup menu.

Incorrect current limits can cause nuisance STO activation or inadequate protection

Reset Drive Fault

After resolving root cause, reset drive fault using drive reset function or cycle 24V control power to drive amplifier.

Some drive faults require specific reset sequence - power cycle may be necessary for certain fault types

Check Machine Parameter 1010

Verify MP1010 (axis configuration) has correct safety function settings for the affected axis channel.

MP1010 bit settings control safety monitoring functions - incorrect bits can cause false alarms

Verify Cut-out Channel Parameters

Check MP1015 through MP1018 for proper cut-out channel configuration and STO monitoring settings for axis A.x.

Cut-out channel parameters must match actual hardware configuration and safety requirements

Review Safety Parameter Backup

Compare current safety parameters with known good backup using TNC backup/restore function to identify parameter changes.

Safety parameter changes require proper validation and may need machine manufacturer approval

Check EnDat Communication

Navigate to Test Run mode, access axis diagnostics, and verify EnDat communication status shows 'OK' for affected axis.

EnDat errors often show as intermittent communication faults in axis diagnostics

Inspect Communication Cables

Check EnDat cable connections at both TNC and drive ends. Verify cable shield continuity and proper grounding.

Power off system before disconnecting EnDat cables to prevent damage

Test Communication Integrity

Use TNC diagnostic functions to test communication quality and signal strength between control and drive.

Poor communication quality often precedes complete communication failure