What causes fault code VFD-RDY1 (VFD Not Ready)?

STO (Safe Torque Off) input not energized. Drive in local mode — not accepting remote commands. Hardware interlock preventing drive start. Pre-charge sequence not complete — capacitors still charging. Drive configuration fault — missing required parameters

How do I fix fault code VFD-RDY1?

Check STO terminals — 24V must be present. Verify drive is in correct control mode (Remote/Network). Check hardware interlock wiring — enable input. Wait for pre-charge to complete (drive LED pattern). Review drive ready conditions in parameter list

VFD Not Ready

VFD-RDY1

Drive reports 'Not Ready' status. Indicates a condition preventing the drive from accepting run commands.

medium vfd

vfd not ready enable sto interlock

Probable Causes (ranked)

STO (Safe Torque Off) input not energized
Drive in local mode — not accepting remote commands
Hardware interlock preventing drive start
Pre-charge sequence not complete — capacitors still charging
Drive configuration fault — missing required parameters

Fix Steps

1 Check STO terminals — 24V must be present
2 Verify drive is in correct control mode (Remote/Network)
3 Check hardware interlock wiring — enable input
4 Wait for pre-charge to complete (drive LED pattern)
5 Review drive ready conditions in parameter list

Field Trick

Check the drive keypad display. Most VFDs show exactly WHY they're not ready. It's almost always STO, mode switch, or enable input.

Suggested Replacement Parts

Parts matched to fault category: Vfd Drive

Allen-Bradley PowerFlex 525 AC Drive 1HP P/N: 25B-D2P3N114 1HP, 480V, 3-phase, built-in EtherNet/IP, EMC filter

AutomationDirect $395.00 Amazon $450.00 Grainger $520.00

ABB ACS580 General Purpose Drive 2HP P/N: ACS580-01-05A7-4 2HP, 480V, built-in safe torque off, adaptive programming

AutomationDirect $425.00 Amazon $480.00 Grainger $550.00

GS20 AC Drive 1HP (Budget Option) P/N: GS20-20P5 1HP, 230V, sensorless vector, compact size — good replacement for testing

AutomationDirect $149.00 Amazon $175.00

Prices are estimates. Verify part numbers match your equipment before ordering.

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