Guides & resources
Guides for the people who keep industrial equipment running
Practical, plain-English guides for maintenance, engineering and purchasing teams: identifying parts and reading nameplates, understanding conditions, sourcing obsolete equipment, migrating legacy PLCs and drives, sizing drives and breakers, buying from abroad, and getting value from surplus, plus an A to Z glossary.
Guides
Written by our team from everyday work buying, identifying, photographing and shipping industrial parts. General guidance only. Always follow the manufacturer's documentation and your site's safety rules.
Allen-Bradley ControlLogix / CompactLogix major fault codes: what they mean and the first checks
Major fault types and codes (T01 power-up to T07 memory), where to read them in Studio 5000, minor vs major vs I/O faults, the first checks and clearing a fault safely.
Siemens S7-300 / S7-400 SF and BF LEDs: what they mean and how to read the diagnostic buffer
SF vs BF (and INTF, EXTF, BUSxF on the S7-400), steady vs flashing, reading the diagnostic buffer in STEP 7, and the first checks for modules, PROFIBUS, PROFINET and backup batteries.
Allen-Bradley SLC 500 fault codes: reading S:1/13 and S:6, the common major errors and how to clear them
The FLT LED, the major error halted bit S:1/13 and the S:6 code, the common powerup, going-to-run, run and I/O errors (xx = the slot), and the ways to clear a fault.
Allen-Bradley MicroLogix FAULT LED flashing or solid red: what it means and how to recover
Flashing red (application fault) vs solid red (hardware fault), finding the code in S:6 or on the 1100/1400 LCD, the common codes, clearing S:1/13 and getting back to RUN.
Allen-Bradley PLC battery low: which battery fits, what the BAT LED means and how to keep the program
The battery for each controller family, what the BAT or BATT LED and the T10:C10 minor fault mean, how long you have, replacing it safely, and whether the program survives.
Allen-Bradley PLC won't go to RUN or stays in PROGram: keyswitch, faults, forces, firmware and I/O
Keyswitch and mode-switch positions, the faults that block RUN, firmware and project mismatches, missing or wrong I/O modules, forces, and the order to check them in.
Siemens S7-1200 / S7-1500 ERROR and MAINT LEDs: what they mean and how to read the diagnostic buffer
RUN/STOP, ERROR and MAINT patterns on S7-1200 and S7-1500 CPUs, the diagnostic buffer in TIA Portal, on the S7-1500 display and in the web server, and the first checks.
PLC I/O module faulted or not responding: status LEDs, connection codes and the first checks
Module status LEDs on ControlLogix, SLC 500, S7-300 and S7-1500 I/O, the Logix connection codes (16#0204, keying 16#0114/0116), power, slot, keying and field wiring checks.
Lost communication to a PLC node: EtherNet/IP, DH+ and DeviceNet LEDs, codes and first checks
1756 EtherNet/IP OK, NET and LINK LEDs and duplicate IP, 16#0203 vs 16#0204, DH+ node addresses and terminators, DeviceNet scanner codes, 121-ohm terminators and bus-off.
PLC power supply failure: symptoms, voltage checks and when to replace it
Symptoms of a failed rack supply, input ranges and outputs for 1756-PA72/PB72/PA75, 1746-P1/P2/P4 and PS 307, Rockwell's and Siemens' checks, and when to replace it.
PanelView Plus won't boot or the touch screen won't respond: status LEDs, startup errors and first checks
FAULT/COMM and STS/ERR LED patterns, the numbered startup errors, configuration, safe and maintenance mode, touch calibration and the .MER version rule.
ControlLogix 1756-ENBT, EN2T and EN2TR faults: OK, NET and LINK LEDs, display messages and connection codes
The status display messages, OK/NET/LINK LEDs, duplicate IP rules, rotary switches and 888, Logix connection codes and the diagnostic web pages (CPU, duplex, errors).
Kinetix 300, 350 and 5500 servo drive faults: reading the display, common faults and safe torque-off
E, F and FLT S codes on the Kinetix 300, 350 and 5500, first checks for overcurrent, bus voltage, overtemperature and feedback faults, and safe torque-off faults.
VFD ground fault or overcurrent trip: what it means, the parameters to read first and safe insulation checks
Ground fault and overcurrent codes on PowerFlex 4, 40, 525, 70 and 750 and SINAMICS G120, the fault parameters to read first and insulation checks with the drive disconnected.
How to calibrate a Rosemount 3051 pressure transmitter with a HART communicator
Zero trim, sensor trim and D/A trim explained, when to use each, the Fast Keys for each device revision, and the procedure on a communicator or documenting calibrator.
How to calibrate an Endress+Hauser iTEMP TMT82 temperature transmitter
Simulating the input, sensor trimming vs current trimming, sensor-transmitter matching with CvD coefficients, and the menu paths for firmware 01.01 and 01.02.
HART communicator vs documenting calibrator: AMS Trex, 475, Fluke 754 and Beamex MC6 compared
A side-by-side comparison from the manufacturers' documents, the 475-to-Trex transition, why device descriptions matter, and which tool fits which job.
HART loop basics for calibration: the 250 Ω resistor, loop power and where to connect
The HART signal, loop resistance and power, parallel connection, safe-state rules, intrinsic safety and a troubleshooting checklist.
Allen-Bradley PLC-5 (1785/1771) lifecycle status: what Rockwell says and what to do
The manufacturer's status and date for common 1785 processors and 1771 modules, Rockwell's ControlLogix migration path, and what to do now.
Allen-Bradley MicroLogix 1000, 1200 and 1500 lifecycle status: what Rockwell says and what to do
The manufacturer's status and date for 1761, 1762 and 1764 controllers, plug-ins and I/O, Rockwell's migration path, and a practical plan.
Allen-Bradley PanelView Plus 6 (2711P) lifecycle status: what Rockwell says and what to do
The manufacturer's status, date and named replacement for common 2711P terminals and modules, and what to check before you move to a PanelView Plus 7.
PowerFlex 70 (20A) lifecycle status: what Rockwell says and what to do
Rockwell's PowerFlex 70 notice, the status and date for common 20A catalog numbers, where the dates differ, and a practical plan.
Siemens SIMATIC S5 and S7-300 lifecycle status: where to check it and what to do
Where Siemens publishes each S5 and S7-300 order number's lifecycle status, what its S7-300 page says about availability, and what to do.
Manufacturer lifecycle status for obsolete automation parts, family by family
Active, Active Mature, End of Life and Discontinued in plain English, how to check a part, and family pages with the manufacturer's own dates.
Allen-Bradley SLC 500 (1746/1747) lifecycle status: what Rockwell says and what to do
The manufacturer's status and date for each common 1747 processor and 1746 module, Rockwell's migration path, and what to do about it now.
PowerFlex 4 and PowerFlex 40 (22A / 22B) lifecycle status: what Rockwell says and what to do
The manufacturer's status, discontinued date and named replacement for each common 22A and 22B catalog number, and a practical plan.
Data center power parts: what’s in the power chain and what to keep on the shelf
MV switchgear, transformers, switchboards, generators, UPS, PDUs and rack power: the replaceable parts at each stage and the spares worth keeping.
How to read breaker and VFD nameplates (and find the date code)
Frame, trip and interrupting ratings on breakers; input, output, duty ratings and series on drives, and where to look for the date of manufacture.
MRO and industrial parts glossary: the terms buyers and technicians use, A to Z
Short, plain-English definitions of the words on labels, listings and purchase orders, from AIC to VFD, with links to the guides that go deeper.
How to read a servo motor nameplate: torque, speed, feedback, brake and fit
Torque, speed and current ratings, voltage class, encoder or resolver feedback, holding brake, flange and IP rating, and how to match a motor to its drive.
How to read Siemens order numbers (MLFB), product versions and firmware
What the 6ES7, 6SL3, 3RT and 3VA prefixes mean, where to find the product version and firmware, and what to check before you swap a Siemens part.
Reading a motor nameplate and sizing a replacement VFD
What every field on a NEMA or IEC motor nameplate means, and how to turn it into the right replacement drive: current, duty, input and derating.
Buying industrial parts from the US: a guide for international buyers
Payment in US dollars, $110 flat shipping per order, duties and paperwork, and how to check voltage, frequency and certification marks before you buy.
How to read an Allen-Bradley catalog number (and what “Ser B” means)
Bulletin numbers, module codes, suffixes, the series letter and firmware revision, and how each one affects whether a replacement will work.
New, new surplus, used, refurbished, for parts: what industrial part conditions mean
Plain-English meanings of every condition grade you'll see on surplus industrial parts, and the questions to ask before buying each one.
How to source obsolete and discontinued automation parts without long downtime
What to do the day a discontinued PLC, drive or HMI fails, and how to stop it from being an emergency next time.
SLC 500 end of life: keep it running on spares or migrate to CompactLogix
Where the SLC 500 stands, which spares keep one running, and how a phased move to CompactLogix keeps downtime short.
Finding obsolete Siemens, GE Fanuc and Fanuc parts: labels, versions and sourcing
How to read Siemens order numbers, GE Fanuc catalog numbers and Fanuc part numbers, which version details matter, and where surplus fits.
VFD basics for maintenance teams: sizing, replacing a failed drive and common faults
Sizing a variable frequency drive correctly, swapping a failed one with minimal downtime, and what the most common fault codes usually point to.
PowerFlex 525 vs PowerFlex 40: replacing a 22B drive with a 25B (or not)
Footprint, terminals, parameters, EtherNet/IP and Safe Torque Off: how to migrate from a PowerFlex 40 to a 525, and when not to.
Molded case circuit breakers: reading the ratings and finding a replacement
Frame size, trip rating, interrupting rating (kA), voltage and slash ratings, trip units and mounting, and a checklist for a safe replacement.
Selling surplus industrial inventory: how to get the best offer
What surplus buyers look at, how to photograph and list your parts, and the simple steps that turn a pile of spares into a fast, fair offer.
Plant decommissioning and facility cleanout checklist for owners, landlords and lenders
Planning, energy isolation, records, recovering value from inventory, removal and a broom-clean handback: a checklist for owners, landlords and lenders.
Data center electrical and controls spare parts: what to keep on the shelf
How to build a critical-spares list for power distribution, UPS, cooling and building controls, and how to rank what earns a place on the shelf.
Manufacturer lifecycle status
Is it discontinued? The manufacturer's own status, dates and named replacements for common legacy families, each line linked to its source. What the lifecycle statuses mean.
Fault code lookup
What a drive's fault code means and what to check first, family by family, each code checked against the manufacturer's own manual, which every page cites. All fault code pages.
Calibration
Field procedures for HART transmitters, from the manufacturers' manuals: as-found tests, trims, and the tools to do them with.
Industry pages
The parts each industry buys most, and how we help with in-stock parts, sourcing and surplus.
Quick references
Item conditions
Exactly what each condition on our site means, including New Surplus.
Shipping
How and when orders ship, and what free shipping covers.
Returns
Our plain-English return policy, which covers every item.
FAQ
Answers to the questions buyers ask us most.
Can't find a part?
Send the part number (one line or a whole ISO list) and we'll check our shelves and our sourcing network.
KIV Industrial Parts is an independent seller of surplus industrial parts and is not affiliated with, or an authorized distributor of, any manufacturer named here. Brand names and part numbers are used only to identify products; they are trademarks of their owners. See our trademark notice.