Kinetix 5500 (2198-Hxxx) and Kinetix 5700 (2198-Sxxx/2198-Dxxx inverters, 2198-Pxxx DC-bus power supplies, 2198-RPxxx regenerative bus supplies) share one fault naming scheme: the drive LCD shows text such as "FLT S33 – BUS UNDERVOLT FL", while in Studio 5000 Logix Designer the fault shows in the axis state, the fault log and the module faults. This article explains how to read faults, what the common codes mean, why on a Kinetix 5700 you check the DC-bus power supply first, and how to reset safely. The Kinetix 5300 displays faults differently, see Kinetix 5300 fault codes.
Where the fault shows
The LCD on the drive
The Home screen shows the axis state, the IP address and the DC-bus voltage. At startup the drive runs a self-test, shows its firmware and stops at PRECHARGE (waiting for mains power); once three-phase power is applied, a Kinetix 5500 moves to STOPPED and a Kinetix 5700 DC-bus power supply moves to RUNNING (2198-UM001N p. 106, 132; 2198-UM002Q p. 161, 221). The state the drive stops at tells you where it is stuck:
| State | Meaning |
|---|---|
| STANDBY / CONNECTING | No configuration yet / no connection to the controller |
| CONFIGURING / SYNCING | Receiving configuration / waiting for group sync |
| PRECHARGE | Waiting for mains AC power |
| START INHIBITED | A condition is preventing enable |
| MAJOR FAULTED | A current or past fault is present |
| SHUTDOWN | Shut down, needs a Shutdown Reset |
To read faults: "MAIN MENU" > "FAULT LOG", press select for the list of active faults, press again for details, and ? for suggested fixes. Each drive and power supply keeps the last 128 faults with time stamps in persistent memory; the log cannot be cleared on the module (2198-UM001N p. 144; 2198-UM002Q pp. 229–230). "Encoder Diagnostics" shows "LINK QUAL" (must always be 100%) and "RSSI" (keep at 80–100%); persistently low values point to a poor feedback ground (2198-UM001N p. 103; 2198-UM002Q p. 154).
MOD and NET indicators
| Indicator | State | Meaning |
|---|---|---|
| MOD | Flashing red | Recoverable major fault, for example a wrong configuration |
| MOD | Steady red | Nonrecoverable major fault |
| MOD | Flashing green/red after self-test (5700) | Waiting for safety configuration or for the STO inputs |
| NET | Flashing red | A connection to the drive has timed out |
| NET | Steady red | Duplicate IP address |
Source: 2198-UM001N p. 146; 2198-UM002Q p. 231. The indicators are for diagnostics only and must not be used to judge the state of a safety function.
In Studio 5000 Logix Designer
- AxisState and AxisFault: after a Fault Reset, AxisFault can drop to 0 before the fault is posted again while AxisState still shows faulted; Rockwell advises relying on AxisState only (2198-UM001N p. 144; 2198-UM002Q p. 230).
- Axis fault log and alarm log: each record holds the fault type, code, sub-code, stop action and time stamp; Fault Reset and Shutdown Reset events are logged too. The alarm log records both when an alarm sets and when it clears (MOTION-RM003Q pp. 1173–1177).
- Module Faults: a roll-up of every NODE FLT the drive reports plus synchronization faults detected on the controller side. The controller usually responds with a shutdown action, and getting the module back usually means re-opening its connection or downloading its configuration again (MOTION-RM003Q pp. 78–79, 1166).
- Axis Properties: the response to each exception (Ignore, Alarm, Fault Status Only, Stop Planner, Disable, Shutdown) is set in the "Actions"/"Exceptions" category; only some exceptions are configurable. From v32, "Disable" replaced "StopDrive" as the default (2198-UM001N pp. 149–150; 2198-UM002Q pp. 236–237).
- Some initialization and safety faults appear in the "Quick View" pane as "Initialization Fault" or "Safety Fault" (2198-RD003C).
- If the controller major-faults because of the axis, 1756-RD001 lists it under Type 18: Code 01/02 initialization faults, 03/04 axis faults (standard/manufacturer-specific), 06 module fault, 08 configuration fault. For connection faults 16#0203 and 16#0204 see ControlLogix I/O module faults.
Fault groups
| Prefix | Meaning |
|---|---|
| FLT Sxx / FLT Mxx | Runtime axis fault, standard (S) or manufacturer-specific (M) |
| INIT FLT | Fault during initialization, before enable |
| NODE FLT | Module-level fault that affects every axis |
| NODE ALARM, ALARM | Reported to the controller only, no stop |
| INHIBIT | Condition that prevents enable |
| SAFE FLT | Fault in the safety function |
The suffix FL means a factory limit was exceeded, UL a user-set limit (2198-UM001N pp. 144–145; 2198-UM002Q p. 230). The full list with Rockwell's corrective actions is in the 2198-RD005 (Kinetix 5500) and 2198-RD003 (Kinetix 5700) spreadsheets.
DC-bus power supply versus inverter
A Kinetix 5500 contains both the converter (rectifier) and the inverter in one drive. A Kinetix 5700 splits them: AC supply, precharge and shunt faults belong to the 2198-Pxxx/2198-RPxxx power supply; motor, feedback and output-stage faults belong to the inverter.
- The power supply has no stopping actions. On a power supply, the "Disable" action puts it into Major Fault; its contactor-enable output opens, so the contactor drops out and the whole system loses three-phase power. "Shutdown" has the same effect, but the supply only runs again after a Shutdown Reset (2198-UM002Q pp. 236, 238).
- When the power supply reports S15, S16, S20, S23 or S25, enabled modules in the same bus group report FLT S40 – BUS POWER SHARING (2198-RD003C). If several inverters show S40, read the power supply's fault log first.
- A fault in one bus-sharing group disables only that group's drives; all modules on the same shared-bus hardware must be configured in the same group (2198-UM001N pp. 133–134; 2198-UM002Q p. 222).
- The 2198-RPxxx regenerative bus supply adds AC line faults S64–S76 (voltage, frequency, unbalance, sag, synchronization) and FLT M29 when the AC line contactor is missing or miswired (2198-UM002Q p. 239; 2198-RD003C).
Common fault codes
"Check first" summarizes 2198-RD003C and 2198-RD005B.
| Code | Meaning | Module | Check first |
|---|---|---|---|
| FLT S07 / S08 – MTR OVERLOAD | Motor thermal model over the factory / user limit | Inverter | Motion profile (lower speed, longer time); for UL review the limit |
| FLT S10 – INV OVERCURRENT | Output current over the instantaneous limit | Inverter | Shorted power cable or motor winding, wire gauge, acceleration time |
| FLT S16 – GROUND CURRENT | Excessive ground current | 5500, single-axis inverters, power supplies | Motor power wiring and cable; DC-bus wiring if a capacitor module is used |
| FLT S20 – CONV OVERLOAD FL | Converter thermal overload | Power supplies, 5500 | Number of drives sharing the bus, duty cycle |
| FLT S23 – AC PHASE LOSS | One input phase lost | Power supplies, 5500 | Measure voltage on all three phases |
| FLT S25 – PRECHARGE FAILURE | DC bus did not reach the expected level after charging, or is too high | Power supplies, 5500 | Input voltage and wiring; inverter or motor shorted to ground; total bus capacitance |
| FLT S33 / S34 – BUS UNDERVOLT | DC bus low | Inverters, 5500 | Incoming AC level, line sags or glitches |
| FLT S35 – BUS OVERVOLT FL | DC bus high | All types | Decel profile; with all power removed and the DC bus measured as discharged (wait at least 5 minutes; 2198-UM001N p. 154; 2198-UM002Q p. 247), unplug the shunt connector and measure the resistor (S31 is a shorted shunt); consider an external shunt; long DC-bus cables increase overshoot |
| FLT S37 – BUS POWER LOSS | DC bus below the threshold for more than 50 ms | 5700 inverters | AC line; the default threshold equals about 150 V DC droop from 650 V DC |
| FLT S38 – FUSE BLOWN | Internal DC-bus fuse blown | 5700 inverters | Return the drive for repair if it continues |
| FLT S45 / S47 – FDBK COMM / DEVICE FAILURE | Feedback data lost / encoder reports an internal error (sub-code nn) | Inverter | Cable, connector, shields, motor frame ground, vibration; for S47 cycle control power |
| FLT S54 / S55 – POSN / VEL ERROR | Position / velocity error over tolerance | Inverter | Tuning, feedforward, drive/motor sizing, power wiring |
| FLT S61 – ENABLE INPUT | Enable input dropped while enabled | Inverters, 5700 power supplies | Input wiring; check that the enable input is assigned as intended; do not remove an enable that is part of the machine's interlocks |
| FLT M25 – DC COMMON BUS | AC present while configured for shared DC | 5500 | Power configuration in Logix, wiring |
| INIT FLT M03 – MTR ENC STARTUP | Encoder communication could not be established at startup | Inverter | Feedback connector, shield terminations |
| NODE FLT 01 / 06 / 07 | Lost updates / lost connection / clock sync lost | All modules | Ethernet cable, switch, number of devices on the motion network, separating signal and power wiring |
| SAFE FLT 09 – SS IN | The two STO inputs disagree for more than 1 second, or re-trigger faster than 1 second | Inverter (hardwired STO) | STO terminations, connector fully seated, 24 V supply, state of both inputs |
Source: fault names and modules from 2198-UM001N Tables 69–71 (pp. 151–152) and 2198-UM002Q Tables 136–149 (pp. 237–245); meaning and checks from 2198-RD005B and 2198-RD003C.
Kinetix 5700 -ERS3 inverters: for SAFE FLT codes see 2198-UM002Q chapter 9 (p. 262 hardwired, p. 275 integrated); for -ERS4 Rockwell points to 2198-RM001 (2198-UM002Q pp. 230–231). SIL levels and safety values must be determined by a competent engineer per ISO 13849-1 / IEC 62061 for each project.
Order of checks
- Record before resetting: the LCD code, fault log, AxisState, which module faulted first.
- Kinetix 5700: power supply first. If inverters show S40 or INHIBIT S06 (the converter asked them to stop drawing bus power), the root cause is in the power supply.
- Power-up order: 24 V first, wait for PRECHARGE, then three-phase power so the shunt is enabled and nuisance overvoltage faults are avoided. If DC BUS does not reach the expected level, check the three-phase connections. Once mains power is on, allow up to 1.8 seconds before the drive is ready for motion commands (2198-UM001N p. 132; 2198-UM002Q p. 221).
- Network: NET indicator, cables, switch, duplicate IPs. On a Kinetix 5700, Rockwell recommends keeping the default "Connection Loss Stopping Action" (Current Decel & Disable) and using DLR where connection loss must be minimized (2198-UM002Q p. 241).
- Motor and feedback: wiring, connectors, shield grounding, LINK QUAL, RSSI.
- Mechanics and profile: coupling, brake, jams, duty cycle.
Clearing the fault safely
- The drive clears the fault only when it receives a Fault Reset from the controller (for example MAFR) and the cause is gone; if still active, it is posted again after a delay (2198-UM001N p. 144; 2198-UM002Q p. 230). A nonrecoverable fault needs a power cycle or device reset (MOTION-RM003Q p. 45). The Shutdown action needs a Shutdown Reset (2198-UM002Q p. 236).
- Do not defeat the drive's fault circuits: find and correct the cause before running again (2198-UM001N p. 143; 2198-UM002Q p. 229).
- Clearing a fault can restart motion. Before resetting, make sure nobody is inside the hazard zone and follow the site's lockout and permit-to-work rules.
- SAFE FLT 09: it can be reset only after both STO inputs have been OFF for more than 1 second, then an MAFR is needed. After work on the STO circuit, run the STO function to confirm it works (2198-UM001N p. 160; 2198-UM002Q pp. 263–264).
- Integrated STO on a Kinetix 5700: the safety fault clears on a rising edge of SO.Reset after SO.SafeTorqueOff has gone to 1; Axis.SafetyFault needs an MAFR (2198-UM002Q p. 274).
- Before working on a module: remove all power, wait 5 minutes and measure to confirm the DC bus has discharged (2198-UM001N p. 154; 2198-UM002Q p. 247).
When to suspect hardware
- MOD steady red.
- Codes for which the spreadsheet says to return the drive for repair if the fault continues: FLT S38, FLT M26 (firmware runtime error), NODE FLT 02 (watchdog), NODE FLT 03 (hardware). SAFE FLT 09 that remains after wiring and supply are checked: return the drive to Rockwell (2198-RD003C, 2198-RD005B).
- Replacing a module: the new one must have the same catalog number if you reuse the existing project; note the IP settings before removal (2198-UM001N p. 153; 2198-UM002Q p. 247). A replacement drive that was used before must be cleared by authorized personnel (Kinetix 5500: out-of-box state; Kinetix 5700 integrated safety: Hardwired STO mode); until the safety controller configures it again, integrated STO protection is not provided (2198-UM001N pp. 169–171; 2198-UM002Q pp. 251, 255–256, 275).
What to record before calling for support
- Catalog number and firmware of each module ("Drive Info" or "Module Info" menu).
- Fault logs of the power supply and the inverters involved, AxisState, a Quick View screenshot.
- Motor catalog number, feedback type, Logix Designer version, bus-sharing group configuration.
- When it happens: power-up, enable, acceleration or stopping; plus a copy of the project.
Need an engineer to check it on site: request support. Running Kinetix 6000 and planning a move to Kinetix 5700: see Kinetix servo migration paths.
Frequently asked questions
What is the difference between FLT, INIT FLT, NODE FLT and SAFE FLT on Kinetix 5500/5700?
FLT Sxx/Mxx are runtime axis faults, INIT FLT are faults during initialization before enable, NODE FLT are module-level faults that affect every axis, and SAFE FLT are faults in the safety function. The suffix FL means a factory limit was exceeded, UL a user-set limit.
Why do several Kinetix 5700 inverters show FLT S40 at once?
FLT S40 – BUS POWER SHARING means the power supply feeding the DC bus asked the module to stop drawing power. Read the fault log of the 2198-Pxxx or 2198-RPxxx power supply to find the root fault, for example S23 or S25.
What should be checked for FLT S35 Bus Overvoltage on a Kinetix 5500/5700?
Check the deceleration profile of the drives sharing the DC bus; with all power removed and the DC bus measured as discharged (wait at least 5 minutes; 2198-UM001N p. 154; 2198-UM002Q p. 247), unplug the shunt connector and measure the resistor; consider an external shunt. Apply 24 V before three-phase power so the shunt is enabled.
How do you clear a Kinetix 5500/5700 fault?
Send a Fault Reset from the controller, for example MAFR, once the cause is gone; the Shutdown action also needs a Shutdown Reset. The 128-fault log on the drive cannot be cleared. Clearing a fault can restart motion, so make sure nobody is inside the hazard zone.
How do you handle SAFE FLT 09?
The two STO inputs disagree: check the STO terminations, connector, 24 V supply and the state of both inputs. The fault can be reset only after both inputs have been OFF for more than 1 second, followed by an MAFR and a test of the STO function; if it remains, return the drive to Rockwell.
Sources
- Rockwell Automation, 2198-UM001N-EN-P, Kinetix 5500 Servo Drives User Manual, 09/2024 — p. 103, 106, 132–134, 143–146, 149–154, 160, 169–171
- Rockwell Automation, 2198-UM002Q-EN-P, Kinetix 5700 Servo Drives User Manual, 06/2026 — p. 154, 161, 221–222, 229–245, 247, 251, 255–256, 262–264, 274–275
- Rockwell Automation, MOTION-RM003Q-EN-P, Integrated Motion on the EtherNet/IP Network Reference Manual, 09/2025 — p. 45, 78–79, 1166, 1173–1177
- Rockwell Automation, 1756-RD001F-EN-P, Logix 5000 Controller and I/O Fault Codes (spreadsheet), 09/2025 — Type 18 (CIP Motion)
- Rockwell Automation, 2198-RD003C-EN-P, Kinetix 5700 Servo Drive Fault Codes (spreadsheet), 05/2024 — sheets FLT Sxx, FLT Mxx, INIT FLT, INHIBIT Sxx, NODE FLT, Hardwired STO
- Rockwell Automation, 2198-RD005B-EN-P, Kinetix 5500 Servo Drives Fault Codes Reference Data (spreadsheet), 09/2024 — sheets FLT Sxx, FLT Mxx, NODE FLT, Hardwired STO
Read 27 October 2026. This article paraphrases the sources and does not quote them; read the original documents before designing or working on a system.