Applicable Systems
EFC
FEX
FEI
HNC
Symptoms
Bus interruption detected. The drive has detected a complete loss of communication on the fieldbus, with no telegrams received within the monitoring time.
Possible Causes
- Fieldbus cable completely severed or disconnected
- Fieldbus switch failure or power loss
- Master controller power failure or crash
- Communication interface hardware failure on the drive
Troubleshooting Steps
- Step 1: Check fieldbus cable continuity from master to drive
Cable is intact end-to-end; no breaks or disconnections - Step 2: Verify fieldbus switch/repeater power and status
Switch is powered; all ports show active link - Step 3: Check master controller power and status
Master is powered on and in RUN mode - Step 4: If all external components are good, the drive's communication interface may be defective
Communication interface hardware test passes in IndraWorks AS
How to Reset
1) Check cable. 2) Verify switch. 3) Check master. 4) Test drive comms interface. 5) Replace defective component.
Frequently Asked Questions
- Q: What is the bus monitoring time?
Typically 3-5 communication cycles (3-10ms). If no valid telegram is received within this time, F4009 triggers. The exact value depends on the communication cycle time setting.
- Q: What happens to motor motion during bus interruption?
The drive activates its configured bus fault reaction: Safe Torque Off (immediate stop), Safe Stop 1 (controlled deceleration), or Hold Last Setpoint. The reaction depends on the safety configuration.
Source: Rexroth IndraDrive HCS/HMS Fault Code List, Bosch Rexroth AG
Category: PLC & VFD