Most of the codes on this page are not reporting a broken drive, they are reporting a condition in the installation that the drive was the first thing to notice, which is why a 525 that eats the same code every summer, every washdown, or every time the big compressor starts is describing the plant it lives in rather than describing itself. The codes are laid out here in the order you actually meet them rather than in numerical order, and where a fault behaves differently on a PowerFlex 523 than on a 525 the entry says so.
Before you clear anything
A reset erases the story, so before anyone touches the keypad it is worth writing down the exact code, what the motor was doing when it tripped, and what changed recently, because starting, accelerating, running steady, decelerating and sitting at power-up are five different answers and the drive will not tell you which one it was once the fault is gone.
Timing is the most underused clue in drive work, since a trip on acceleration points at ramp time and inertia and current limit, a trip at steady state points at load and cooling and sizing, a trip on deceleration points at regeneration, and a trip at power-up points at wiring and precharge and the supply. That single observation narrows the field further than most of the electrical testing that usually gets done first.
Lock out and tag out before the enclosure comes open, verify the DC bus has discharged and honor the stated wait time before touching bus terminals, and match the PPE to the arc flash rating, because none of the codes below are worth working live for.
One fault language, two drives
The 523 and the 525 share a fault map, the same numbers and names and 16 character display strings, and they share power modules as well, which is why the two can be carried on one shelf and why a control module swap between them is a real service option rather than a theory. Five faults exist only on the 525 because they belong to hardware the 523 does not have, those being F059 and F111 for the safety inputs, F073 and F083 for embedded EtherNet/IP, and F091 for the encoder, so if you are working a 523 and chasing one of those you are on the wrong drive.
The numbering itself goes back much further than the 520 series does. F002 Auxiliary Input, F003 Power Loss, F005 OverVoltage, F012 HW OverCurrent and F013 Ground Fault sit at the same numbers on a PowerFlex 70 and a PowerFlex 4, so a technician who learned these codes on a 700 fifteen years ago still carries most of what he needs, which is not something that holds when you cross between manufacturers.
How Allen-Bradley tells you something is wrong
A fault on a 525 shows up as a flashing fault number and a flashing fault LED, and that is the whole display vocabulary, because there is no yellow warning tier and no advisory class on this drive the way there is on some others. Every code on this page stops the motor.
What the 525 has instead is a two type system, and it is the most useful column in the manual. A Type 1 fault is Auto-Reset and Run, meaning that if A541 [Auto Rstrt Tries] is set above zero the drive waits out A542 [Auto Rstrt Delay] and attempts its own reset, while a Type 2 fault is Non-Resettable and will not clear until the cause is corrected, which is the drive’s way of saying it suspects damage, wiring, or a programming error rather than a passing condition. Every entry below carries its type, and reading that column first will usually tell you how hard to worry before you have measured anything.
Warning level information does exist on a 525, it just lives on the relay and opto outputs instead of on the display, and almost nobody sets it up. Output function 16, Thermal OL, energizes when the motor overload counter passes the level you set and also when the drive comes within 5 degrees C of its own overheat trip, which makes it a genuine pre-trip warning available on a dry contact. Function 9, Retries Exst, reports that the drive used up its restart attempts, function 14, NonRec Fault, covers a non-resettable fault or a drive with auto restart turned off, function 17 reports control module over temperature, and function 19 reports comm loss from any source carrying reference or control. If you want this drive to warn you before it trips, that is where the warning gets built.
The quick table
| Code | Name | Type | On a 523 |
|---|---|---|---|
| F000 | No Fault | yes | |
| F002 | Auxiliary Input | 1 | yes |
| F003 | Power Loss | 2 | yes |
| F004 | UnderVoltage | 1 | yes |
| F005 | OverVoltage | 1 | yes |
| F006 | Motor Stalled | 1 | yes |
| F007 | Motor Overload | 1 | yes |
| F008 | Heatsink OvrTmp | 1 | yes |
| F009 | CC OvrTmp | 1 | yes |
| F012 | HW OverCurrent | 2 | yes |
| F013 | Ground Fault | 1 | yes |
| F015 | Load Loss | 2 | yes |
| F021 | Output Ph Loss | 1 | yes |
| F029 | Analog In Loss | 1 | yes |
| F033 | Auto Rstrt Tries | 2 | yes |
| F038 | Phase U to Gnd | 2 | yes |
| F039 | Phase V to Gnd | 2 | yes |
| F040 | Phase W to Gnd | 2 | yes |
| F041 | Phase UV Short | 2 | yes |
| F042 | Phase UW Short | 2 | yes |
| F043 | Phase VW Short | 2 | yes |
| F048 | Params Defaulted | 1 | yes |
| F059 | Safety Open | 1 | no |
| F063 | SW OverCurrent | 1 | yes |
| F064 | Drive Overload | 2 | yes |
| F070 | Power Unit | 2 | yes |
| F071 | DSI Net Loss | 2 | yes |
| F072 | Opt Net Loss | 2 | yes |
| F073 | EN Net Loss | 2 | no |
| F080 | Autotune Failure | 2 | yes |
| F081 | DSI Comm Loss | 2 | yes |
| F082 | Opt Comm Loss | 2 | yes |
| F083 | EN Comm Loss | 2 | no |
| F091 | Encoder Loss | 2 | no |
| F094 | Function Loss | 2 | yes |
| F100 | Parameter Chksum | 2 | yes |
| F101 | External Storage | 2 | yes |
| F105 | C Connect Err | 2 | yes |
| F106 | Incompat C-P | 2 | yes |
| F107 | Replaced C-P | 2 | yes |
| F109 | Mismatch C-P | 2 | yes |
| F110 | Keypad Membrane | 2 | yes |
| F111 | Safety Hardware | 2 | no |
| F114 | uC Failure | 2 | yes |
| F122 | I/O Board Fail | 2 | yes |
| F125 | Flash Update Req | 2 | yes |
| F126 | NonRecoverablErr | 2 | yes |
| F127 | DSIFlashUpdatReq | 2 | yes |
The code is the back end of the job
This page gets you through the fault in front of you. Before the First Fault is the full reference, plus the install and commissioning practice that stops most of these from happening at all.
The fault details
F002 Auxiliary Input, Type 1
What it means. An external trip input opened, which means something in somebody’s interlock chain did exactly what it was installed to do.
Most likely cause. A safety device, a limit switch, a thermostat or a permissive somewhere upstream of the drive, although it can also be a deliberate fault written over the network, and those two look identical from the keypad.
The fix, in order. Find what opened before clearing it, since clearing first throws away the only evidence there was, then check the remote wiring back through the chain, and if the drive is under network control verify the communications programming as well, because a fault the PLC wrote on purpose reads the same as a wire that fell off a terminal.
When to stop. If the chain tests good and it keeps tripping you are chasing an intermittent contact or a vibration problem, which is a mechanical hunt rather than an electrical one.
F003 Power Loss, Type 2
What it means. The drive detected single phase operation with a load on it, and Rockwell classed it non-resettable, which tells you they consider it a condition capable of damaging something.
Most likely cause. A blown input fuse, a loose line side connection, or a utility event, and since single phasing under load is hard on both the bus capacitors and the input rectifier, the non-resettable classification is doing real work here.
The fix, in order. Measure all three phases at the drive input terminals rather than at the disconnect so the wiring between them is included in the test, check the input fuses individually because one open fuse is the classic cause and does not announce itself, then look at whether the trip lines up with something large starting elsewhere on the same bus.
When to stop. If it happens on a schedule, log it against time of day and against the other big loads in the plant, since power loss and undervoltage that keep office hours are usually the utility or a shared feeder rather than anything inside the panel.
F004 UnderVoltage, Type 1
What it means. DC bus voltage fell below the minimum the drive will run on.
Most likely cause. A sag, a brownout, a soft supply, or a line side connection that is loose enough to open up under load and tight enough to read fine with a meter at rest.
The fix, in order. Monitor the incoming line for low voltage and interruptions over enough time to catch the pattern rather than taking one reading, torque the line side terminations while you are in there, and compare against the other drives on the same feeder, because one drive tripping while nine others ride through points at that drive’s wiring rather than at the plant’s distribution.
F005 OverVoltage, Type 1
What it means. DC bus voltage went above the maximum, which on deceleration means the load is pushing energy back into the bus faster than the drive can absorb it.
Most likely cause. Regeneration on decel is the common version by a wide margin, and at steady state or idle the answer is usually line voltage running high or a transformer tap set for a different service than the one you have.
The fix, in order. If it trips on decel extend the decel time first, since that costs nothing and works more often than people expect, and if the process will not tolerate a longer ramp then the energy needs somewhere to go, which means a dynamic brake resistor rather than more parameter work.
When to stop. A high inertia load that has to stop fast is a braking problem and not a tuning problem, so once the ramp is as long as the process allows, further adjustment is just moving the trip around.
F006 Motor Stalled, Type 1
What it means. The drive could not accelerate or decelerate the motor, because output current sat against the limit longer than the drive was willing to allow.
Most likely cause. The load is not moving the way the drive expects it to, whether that is a jammed conveyor, a seized bearing, frozen product, an undersized drive, or an accel ramp asking for more current than the limit will supply.
The fix, in order. Turn the shaft by hand if that can be done safely, since ruling a mechanical bind in or out takes half a minute and saves an hour of parameter work, then increase the accel time in P041 or in A442, A444 and A446 [Accel Time x], or reduce the load, so that output current stops running against A484 and A485 [Current Limit x]. An overhauling load produces the same code from the opposite direction and is worth checking before you conclude the ramp is at fault.
When to stop. If the drive stalls with the coupling removed the problem is the drive or the motor, and if it only stalls coupled the problem is the machine.
F007 Motor Overload, Type 1
What it means. The drive’s electronic overload accumulated too much motor current over time, which makes this a thermal model rather than an instantaneous trip.
Most likely cause. A genuinely overloaded motor, a wrong value in P033 [Motor OL Current], or mechanical drag that has been building for months and only now crossed the threshold.
The fix, in order. Read the motor nameplate and confirm P033 actually matches it, because a wrong overload setting causes this code more often than an overloaded motor does and costs nothing to check, then reduce the load if the current turns out to be real, and verify A530 [Boost Select] as well, since too much boost at low speed pushes current into the motor without producing useful work.
When to stop. If the current sits right at nameplate and has been climbing slowly over weeks, the drive is giving you early warning of a mechanical wear problem, which is the outcome you want from a protective device.
F008 Heatsink OvrTmp and F009 CC OvrTmp, both Type 1
What it means. F008 is the power module heatsink over temperature and F009 is the control module, so they are two different sensors pointing at two different places even though the environmental causes overlap heavily.
Most likely cause. For F008, a dirty or blocked heatsink, a failed fan, a hot cabinet, or a carrier frequency set high in an enclosure that cannot carry the extra switching loss, and for F009 the same environment, except that if the cabinet is genuinely cool then the control module itself becomes the suspect.
The fix, in order. Measure the actual ambient at the drive intake rather than in the middle of the room, since those two readings are frequently 15 degrees apart, then clean the heatsink fins, which on a 525 in a dusty plant is usually the entire answer, confirm the fan is turning and turning the correct direction, and look at what the carrier frequency is set to, because every kilohertz above the rating point spends thermal headroom you may want back in August.
When to stop. If the ambient is inside spec and the fins are clean and the fan runs, you are looking at a drive undersized for its duty cycle or a cabinet that needs cooling, and neither of those gets solved at the keypad.
F012 HW OverCurrent, Type 2
What it means. Output current exceeded the hardware current limit, which is the instantaneous trip where the drive protects its own power devices in microseconds, and the non-resettable classification is the drive telling you it suspects something may already be damaged.
Most likely cause. A short circuit, a ground fault on the output, or a violent load event, though it can also be programming, specifically too much boost or DC brake volts set too high.
The fix, in order. Resetting into a short is how a repairable drive becomes a replaced one, so disconnect the motor leads at the drive and megger the cable and the motor separately before energizing anything again, which tells you which of the two you are dealing with. If both test clean, go back to A530 [Boost Select] and the DC brake settings, and look at what the load is doing in the instant before the trip rather than at what it does while running.
When to stop. If it trips instantly on start with the motor connected and does not trip with the motor disconnected, the answer is out in the plant and further work at the drive is wasted.
F013 Ground Fault, Type 1 with one exception
What it means. Current found a path to earth ground at one or more of the output terminals.
Most likely cause. Moisture in a peckerhead, damaged cable insulation, a washdown motor coming to the end of its life, or a conduit fitting that has been filling with water since spring and nobody opened.
The fix, in order. Megger the motor and the cable separately, since splitting them tells you whether you are pulling a motor or pulling a cable, and open the peckerhead and look while you are there, because water and corrosion are visible and cost nothing to check. On a long or buried run it is worth meggering from both ends.
Worth knowing. F013 behaves differently from every other fault on this drive, in that it can be cleared by the auto restart routine but is attempted exactly once and ignores whatever value you set in A541. That is a deliberate compromise between a ground fault that is moisture which dried out overnight, worth a single try, and one that is a motor coming apart, worth none.
When to stop. A megger reading that is low and getting lower across successive checks is a motor scheduled for failure, so the useful move at that point is planning the outage rather than continuing to test.
F038, F039 and F040 Phase U, V and W to Ground, all Type 2
What it means. The same physical event as F013, except that the drive names the leg it found it on.
Most likely cause. The same list as F013, narrowed to one conductor.
The fix, in order. Start the megger work on the named leg, since the drive has already eliminated two thirds of the field, then check the wiring between the drive and the motor on that phase before checking the motor winding itself.
Worth knowing. Naming the phase is real diagnostic resolution and a fair number of competing drives do not offer it, giving one earth fault code and leaving the leg to you.
When to stop. If the fault will not clear with the motor leads removed and an output megger reads clean, the output section of the drive is suspect and the conversation turns to replacement.
F041, F042 and F043 Phase Shorts, all Type 2
What it means. Excessive current between two output terminals, with F041 being U to V, F042 being U to W, and F043 being V to W.
Most likely cause. Damaged cable, a failed motor winding, or something conductive where it should not be, which includes a conductor pinched in a gland and a lug sitting against a panel wall.
The fix, in order. Check the motor and drive output terminal wiring on the named pair for a shorted condition and ring out the motor phase to phase, and look inside the drive output terminal box before concluding anything, since a single strand bridging two lugs produces exactly this code and takes five seconds to find.
When to stop. If the wiring and the motor both test clean on the named pair, the output stage has failed, and continuing to reset into it accomplishes nothing.
F015 Load Loss, Type 2
What it means. Output torque current fell below the level programmed in A490 [Load Loss Level] for longer than the time in A491 [Load Loss Time], which means the motor is turning and the load is gone.
Most likely cause. A broken belt, a failed coupling, a sheared key, a snapped chain, or a pump that lost its prime, and this fault is rarely wrong about it.
The fix, in order. Go and look at the machine before doing anything electrical, then verify the connection between motor and load, and afterward confirm that the level and time settings actually match the process, because a light load condition that is normal for your machine will throw this code all day if the level was never tuned.
Worth knowing. This one is Type 2, so a broken belt will not auto clear and restart, which is the correct decision and occasionally surprises people who assumed the drive would ride through it.
F021 Output Ph Loss, Type 1
What it means. An output phase went missing, and this fault only exists if somebody enabled it with A557 [Out Phas Loss En].
Most likely cause. A loose output connection, a failed contactor between the drive and the motor, or a broken conductor, with the contactor being the most common of the three.
The fix, in order. Torque the output terminations at both ends, check any contactor or disconnect sitting between the drive and the motor since that is usually where this lives, then verify the motor windings phase to phase.
When to stop. If you find a burned output lug, understand why it got hot before replacing it, because a lug that has been arcing has usually taken something else with it.
F029 Analog In Loss, Type 1
What it means. An analog input that was configured to fault on signal loss lost its signal, with the behavior set up in t094 [Anlg In V Loss] or t097 [Anlg In mA Loss].
Most likely cause. A broken speed reference wire, a failed transmitter, a loose terminal, or a power supply feeding the transmitter that dropped out and came back.
The fix, in order. Measure the signal at the drive terminals rather than at the transmitter so the wire is included in what you are testing, check the terminal screws since analog terminals are small and get under-torqued as a matter of routine, and confirm the transmitter has power.
When to stop. Analog signal wire sharing a tray or conduit with motor leads will produce this intermittently for as long as it stays there, so if the fault is intermittent and the routing is wrong, the routing is the fault.
F033 Auto Rstrt Tries, Type 2
What it means. The drive tried to reset a fault and resume running for the number of attempts programmed in A541 and the condition never cleared, so this code is not the problem but rather the drive reporting that the real problem kept coming back.
The fix, in order. Read the fault buffer before clearing anything, since b007, b008 and b009 hold the three most recent codes and the drive holds ten, and the fault you should actually be working is in there.
When to stop. Raising A541 to keep production moving converts a diagnosis into a habit, and the drive will go on hiding the underlying fault for as long as you let it.
F059 Safety Open, Type 1, and F111 Safety Hardware, Type 2, neither on a 523
What it means. These two are not the same fault and the difference matters, because F059 means both safety inputs, Safety 1 and Safety 2, are not enabled, while F111 means one of them is not enabled, which is a channel discrepancy and a hardware level problem rather than a circuit that opened normally.
Most likely cause. For F059, the safety circuit is open and doing its job, whether that is an e-stop, a gate switch, a light curtain or a safety relay that dropped out, and for F111, one channel has failed, one wire is off, or the enable hardware itself has malfunctioned.
The fix, in order. For F059, check the safety input signals and trace the circuit back to whatever opened it, and if the machine does not use the safety function then verify and tighten the jumper across I/O terminals S1, S2 and S+. For F111, run the same checks, and if both channels test good the control module becomes the suspect.
When to stop. Jumpering a live safety circuit to clear a fault is not troubleshooting, and turning off the annunciation with t105 [Safety Open En] does not turn off the reason the circuit opened.
F063 SW OverCurrent, Type 1
What it means. The software current trip, which fires when the programmed level in A486 or A488 [Shear Pin x Level] is exceeded for longer than the time set in A487 or A489 [Shear Pin x Time].
Most likely cause. A process excursion rather than a fault, meaning the load did something heavier than the drive was told to tolerate.
The fix, in order. Verify the connections between motor and load, then verify that the level and time settings match what the machine actually does on a bad day rather than what it does on a good one.
Worth knowing. F012 and F063 are the same physical quantity handled two different ways, and the pair is the most useful diagnostic split on this drive, because F012 is a microsecond hardware trip classed non-resettable and therefore points at suspected damage, while F063 is a seconds scale programmed trip classed auto-resettable and therefore points at the process. The code tells you which timescale you are working in before you have measured anything.
F064 Drive Overload, Type 2
What it means. The drive’s own overload rating was exceeded over time, which is the drive reporting that it is too small for the job it has been given or that its cooling has degraded until the effect is the same.
Most likely cause. Undersizing against the real duty cycle, an accel ramp too aggressive for the inertia, or a heatsink and fan that stopped doing their job some time ago.
The fix, in order. Reduce the load or extend the accel time as the immediate action, then go back and check the sizing against the actual duty cycle rather than against the motor nameplate, since those are two different questions and the second one is the one that usually got skipped.
When to stop. If the drive is correctly sized and clean and still overloads, the application changed at some point and nobody wrote it down.
F070 Power Unit, Type 2
What it means. A failure was detected in the drive’s power section, which is a hardware report rather than an installation report.
The fix, in order. Confirm that the maximum ambient temperature has not been exceeded, since heat is the one external factor that produces this, then cycle power once, and if it does not clear the drive is a replacement.
When to stop. One power cycle is the whole allowance here, and repeating it does not improve the odds.
F071, F072 and F073 Net Loss, all Type 2, with F073 on the 525 only
What it means. Control over the network was lost while the drive was being commanded over it, with F071 covering Modbus or DSI, F072 covering the network option card’s remote network, and F073 covering embedded EtherNet/IP.
Most likely cause. Cable, termination, switch port, or whatever is on the far end, and for F072 specifically, card seating comes before any of those.
The fix, in order. Cycle power, check the communications cabling, then check the settings and the status of the far end, and on an option card reseat it before replacing anything.
Worth knowing. This group is about losing control rather than losing communication, so if the drive was not being commanded over that network at the time, the F081 through F083 group is the one that applies.
F081, F082 and F083 Comm Loss, all Type 2, with F083 on the 525 only
What it means. Communication itself was interrupted, with F081 on the Modbus or DSI port, F082 on the option card, and F083 on the internal link to the embedded EtherNet/IP adapter.
Most likely cause. Physical layer, nine times out of ten, and comm cable run alongside power wiring is the repeat offender across this entire family.
The fix, in order. Cycle power and check the cabling and settings, then reroute comm cable away from motor leads if they are sharing a tray or a conduit, which resolves more intermittent comm faults than any parameter change will. Grounding I/O terminals C1 and C2 can improve noise immunity on a bad site and is worth trying, and C125 [Comm Loss Action] should be set deliberately rather than left where it shipped, since that one parameter decides whether a dropped packet stops your process.
When to stop. If the fault only appears when a specific large load starts, the problem is noise and no amount of switch or cable replacement will address it.
F048 Params Defaulted, Type 1
What it means. The drive was commanded to write default values to EEPROM, which means somebody or something wiped the setup.
The fix, in order. Clear the fault or cycle power, then reload the parameters from the saved file, assuming there is one.
Worth knowing. The ten minutes per drive it takes to save parameter files across a plant is the difference between a five minute module swap and a two hour reprogram at 3am with somebody standing behind you.
F080 Autotune Failure, Type 2
What it means. The autotune was either canceled by the user or it failed to complete.
Most likely cause. The motor is not connected, the load is coupled when the procedure requires it uncoupled, or the nameplate data was entered wrong.
The fix, in order. Verify the nameplate entries first, since bad data fails a tune more often than bad hardware does, confirm the motor is connected and the coupling state matches what the procedure requires, then restart it.
F094 Function Loss, Type 2
What it means. The Freeze-Fire input, also called Function Loss, is inactive because the input to the programmed terminal is open.
The fix, in order. Close the input at the terminal and then cycle power, since this fault does not clear on its own, and trace the circuit with the same discipline you would bring to F002.
F091 Encoder Loss, Type 2, 525 only
What it means. One of the two encoder channel signals is missing, which requires a differential encoder to begin with.
The fix, in order. Check the wiring, then the coupling, then the encoder itself. If the drive is set up for positioning with P047, P049 or P051 [Speed Reference x] at 16 and A535 [Motor Fdbk Type] at 5 for Quad Check, try swapping the encoder channel inputs or swapping any two motor leads, because a reversed feedback direction reads to the drive as a lost channel.
F100 Parameter Chksum and F101 External Storage, both Type 2
What it means. F100 is a checksum error in the drive’s parameter storage and F101 is a failure in the external non-volatile storage.
The fix, in order. For either one, set P053 [Reset To Defalts] to 2 for a Factory Reset and reload the parameter file, and if F100 returns after that the drive has a memory problem that is not going to improve.
F105, F106, F107 and F109, the module pairing faults, all Type 2
What it means. These four describe the relationship between the control module and the power module, and they are worth separating because they say four different things. F105 C Connect Err means the control module was disconnected while the drive was powered, F106 Incompat C-P means a PowerFlex 525 control module was mounted on a power module rated 0.25 HP which the 525 control module does not support, F107 Replaced C-P means the control module could not recognize the power module at all, and F109 Mismatch C-P means the control module was mounted to a different drive type power module.
The fix, in order. For F105, clear the fault and verify every parameter setting afterward, and stop pulling control modules with power applied. For F106, either change to a different power module or fit a PowerFlex 523 control module, since that combination is supported where the 525 one is not. For F107, change the power module and replace the control module if that does not resolve it. For F109, set P053 [Reset To Defalts] to 3 for a Power Reset.
Worth knowing. The two piece design is an advantage on a swap and a trap on a mismatch, which is a good argument for labeling the pairs before they get separated on a bench.
F110 Keypad Membrane, F114 uC Failure and F122 I/O Board Fail, all Type 2
What it means. F110 is a keypad membrane failure or disconnection, F114 is a microprocessor failure, and F122 is a failure in the drive control and I/O section.
The fix, in order. Cycle power once on any of the three, and on F114 verify the grounding before concluding anything, since a poorly grounded drive produces microprocessor faults that look like failed hardware and are not. If they do not clear after that, the control module is the replacement item in all three cases.
F125, F126 and F127, the firmware faults, all Type 2
What it means. F125 Flash Update Req means the firmware is corrupt, mismatched, or incompatible with the hardware, F126 NonRecoverablErr means a nonrecoverable firmware or hardware error was detected and the drive stopped and reset itself, and F127 DSIFlashUpdatReq means the drive found a critical firmware problem and is now running on backup firmware that only supports DSI communications.
The fix, in order. For F125, perform a firmware flash update with the correct file over a connection that will not drop partway through, and for F127 do the same thing but over DSI, because that is the only channel the drive has left to talk on. For F126, clear the fault or cycle power once, and if it returns, replace the drive or the control module rather than continuing to cycle it.
The faults you prevent are the ones you never read
The 525 keeps a fault buffer ten deep and almost nobody opens it, which is a mistake, because what it holds is considerably more than a list of codes. For each of the ten the drive stores the fault code, the elapsed time in hours and minutes, the output frequency at the trip, the output current at the trip, the DC bus voltage at the trip, and the drive status word at the trip. The codes are in F601 through F610 and the three most recent also appear at b007, b008 and b009, with the times in F611 through F630, the frequencies in F631 through F640, the currents in F641 through F650, the bus voltages in F651 through F660, and the status words in F661 through F670.
That set of values is a snapshot of what the drive was doing at the instant it stopped, ten events deep, and it answers the question that cannot be answered any other way after the fact, which is what was happening immediately before. A trip at 12 Hz with 180 percent current is a different story from a trip at 58 Hz with nominal current, and the buffer already knows which one you had while you are still standing there guessing.
All of it is parameter data, which means a PLC can read it, so if these drives are on a network and the only thing being pulled is the active fault bit, the entire history is sitting there unused.
The part that catches people is what happens when A541 [Auto Rstrt Tries] is set above zero, because the drive then trips, waits out A542 [Auto Rstrt Delay], resets itself and restarts, and nobody watching the line sees a stop at all. The event exists only in the buffer, so the same feature that keeps production running is the one that hides the evidence, which is the whole argument for reading the buffer before clearing it.
Reading and clearing faults
Press Esc to acknowledge a fault and get the display back, then read b007 [Fault 1 Code] for the most recent one and correct the cause before clearing anything. The fault then clears one of four ways: pressing Stop if P045 [Stop Mode] is set between 0 and 3, cycling drive power, setting A551 [Fault Clear] to 1 for Reset Fault, or using a digital input programmed to 13 for Clear Fault on t062, t063, or t065 through t068 [DigIn TermBlk xx]. Setting A551 to 2 clears the entire buffer, so that value is worth avoiding until the history has been read.
Auto restart ships turned off, with A541 [Auto Rstrt Tries] defaulting to 0 and accepting 0 through 9, and A542 [Auto Rstrt Delay] defaulting to 1 second and accepting 0 to 120. It acts only on Type 1 faults and the Type 2 list is locked out of it entirely, which is the fence Rockwell built around the feature.
There is one more setting that almost nobody uses, and it is worth knowing because of what it says about the design. Put A541 above 0 and leave A542 at 0, and the drive will clear an OverVoltage, UnderVoltage or Heatsink OvrTmp without restarting the motor, which separates clearing the latch from restarting the load and does it for the three faults most likely to be the plant having a bad afternoon rather than the equipment being broken.
Use auto restart deliberately or not at all, since it exists so that a remote pump station or a line running 40 drives can ride through a sag without a truck roll, and consider the local, national and international codes and standards that apply to the machine before enabling it, because a drive that restarts itself is attached to a machine that starts itself.
Where this fits
Fault codes are the back end of the job, and most of what appears on this page was decided months earlier by a cable length, a grounding choice, a cabinet without enough air, or a sizing calculation run off the motor nameplate instead of the duty cycle. If you want fewer of these, the work happens before the first start, which is what the VFD Installation Guide and the VFD Troubleshooting Guide are built around. The same treatment for the other two platforms is in the ABB Drive Fault Field Guide and the Yaskawa Fault Field Guide.
If what you want is the competency behind the codes rather than the codes themselves, that is what the training does, and Before the First Fault is the field record the whole approach came out of.
Fault codes and behavior on this page are taken from the current Rockwell Automation 520-series user manual, publication 520-UM001. Confirm against the manual revision that matches the firmware in front of you. PowerFlex and Allen-Bradley are trademarks of Rockwell Automation, used here for identification.