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Technical articles
Short engineering notes from our migration, maintenance and network work. Each article lists the public Rockwell Automation or vendor publications it is based on.
Fault codes & troubleshooting
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PowerFlex 755T/755TS fault codes (TotalFORCE): how codes are numbered, common faults and safe reset
TotalFORCE drive codes live in the 750-RD102 workbook, and the prefix shows which port raised them (10xxx inverter, 12xxx power layer, 13xxx/14xxx converter, nnxxx options). 19 common codes, what to check and how to reset safely.
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Major faults on ControlLogix, CompactLogix and GuardLogix: reading Type/Code and what to check
A major fault stops a Logix 5000 controller executing logic. Where to read the Type/Code, what the common codes in 1756-RD001 mean (Types 1, 3, 4, 6, 7…), how fault routines and handlers work, and how to clear the fault safely.
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Logix 5000 minor faults: the controller keeps running, but do not ignore them
Minor faults do not stop the machine, so they are often ignored, yet some warn of a bigger failure such as a weak battery or ESM before a power loss. The common codes in 1756-RD001 and how to monitor them in logic per 1756-PM014O.
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ControlLogix and CompactLogix I/O and Connection Fault Codes: 16#0204, 16#0203 and Other Common Codes
Where I/O faults show, how 0x0204, 16#0204 and #0204 relate, and a table of about 20 common I/O and connection codes (lost connections, keying, ownership, produce/consume, firmware) with what to check — from Rockwell's 1756-RD001 and 1756-PM014O.
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ControlLogix 5580 and 1756-EN4TR Syslog: Reading Events to Trace Lost Connections and Unexpected Stops
The ControlLogix 5580 and 1756-EN4TR syslog records power loss, resets, network configuration changes, firmware updates and CIP Security session failures. How to read an entry, the most useful IDs and how to use them for intermittent connection loss — from Rockwell QA66691 and 1756-RD001.
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PowerFlex 525 fault F004 (UnderVoltage) — causes and how to fix it
F004 means the DC bus voltage has dropped below the minimum — almost always caused by the supply, not a failed drive. How to read the fault data, what to check at the panel, and when the drive actually needs replacing.
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PowerFlex 525 faults F005, F007, F013 — meaning, causes and what to check
F005 DC bus overvoltage, F007 motor overload, F013 output ground fault: what each fault means, how to read the fault data, what to check at the panel, which parameters are involved and when to suspect the drive.
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Kinetix 5300 fault codes: reading the drive display and Logix Designer, checks and safe reset
How to read Kinetix 5300 faults on the four-character display, the MOD/NET indicators and the axis in Logix Designer; what the common codes (F33, F35, F54, F61, nF06, SF09…) mean, what to check, and how to reset without unexpected motion.
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Guardmaster 440C-CR30 safety relay fault codes: FAULT indicator, fault type/code and how to clear them
Whether the FAULT indicator flashes or stays red decides how to handle a 440C-CR30 relay. How to read the code in CCW, Studio 5000 and Modbus, what the common codes (10H/08H, 10H/20H, 02H, 04H…) mean and how to clear them in order.
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MicroLogix 1500 faults: FAULT LED, S:6 major error code and how to get back to RUN
A flashing or steady FAULT LED, bit S:1/13 and the major error code in S:6 tell you what is wrong with a MicroLogix 1500. This article explains the common indications (battery, memory module, expansion I/O, missing OS) and the recovery sequence from manual 1764-UM001D.
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PanelView Plus 7 Shows No Data from the PLC: What to Check
Asterisks on the screen do not always mean the PLC is lost. Six checks from Rockwell's documents: the display object, diagnostic messages, Ethernet indicators, the terminal's IP settings (automatic by default), the Runtime (Target) shortcut and the question asked when a .mer file is loaded.
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FactoryTalk View SE Client Cannot Connect or Shows Tag Errors: A Checklist
Same Directory, same version, ping by name and by IP, server states in the System Status Portal, a replaced Directory server, and the firewall ports Rockwell lists in FTSP-RM001.
Migration & upgrade paths
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PLC-5 to ControlLogix Migration: Converting the Program, Keeping or Replacing 1771 I/O, and What the Tool Won't Do
Logix Designer Export converts PLC-5 ladder logic to ControlLogix, but I/O, block transfers, MSG, PID, interrupts and AGA gas-flow routines still need manual work. This article collects those points from Rockwell's 1756-RM085I, how to choose between keeping and replacing 1771 I/O, and the process TDL follows.
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Upgrade Paths for Legacy Allen-Bradley Systems: SLC 500, MicroLogix, 1768, PanelView, FLEX I/O, ControlNet
Rockwell publishes a separate migration document for each legacy product line. This article puts the main paths in one place: the target, what can be kept, what has to be redone by hand, and the publication numbers to look up.
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CompactLogix 1769-L31, L32E, L35E, L23E end of life — migration path to 5370/5380
Four early CompactLogix controllers were discontinued between 2016 and 2020, and the catalog number Rockwell lists as the 'replacement' for the L31 is also discontinued. This article sets out the right path according to Rockwell's lifecycle pages and what to check before converting the program.
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1756-ENBT end of life — replace with 1756-EN2T, EN2TR or EN4TR?
Rockwell discontinued the 1756-ENBT on 31 December 2021. The three current replacements differ in connection count, number of ports, speed and redundancy support — choose the catalog number by the network you have, not by price.
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PowerFlex 755 to 755TS Migration: What Stays, What Changes and a Plant Checklist
From Rockwell's 750-RM102 guide: the 755TS keeps the 755's dimensions, wiring and power rating, but the catalog number, option modules, communication, parameter numbers, software versions and safety option handling change. With a plant checklist.
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Legacy HMI/SCADA: What to Replace RSView32, PanelBuilder32, Wonderware, Citect, WinCC and iFIX With — Paths to FactoryTalk, AVEVA and Ignition
Legacy HMI/SCADA software still runs in many plants in Vietnam but has been discontinued or renamed. This article collects the status published by each vendor, the target platforms TDL proposes (FactoryTalk View/Optix, AVEVA, Ignition), what converts automatically and what has to be redone — with sources.
Networks & OT security
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DLR or PRP: Choosing Redundancy for an EtherNet/IP Network
Device Level Ring tolerates one break and recovers within a few milliseconds; PRP runs two independent networks in parallel, with no recovery time but twice the infrastructure. The numbers and rules to settle before closing the ring.
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Firewalls for FactoryTalk and Logix systems: open the right ports, not "any"
An "any-any" rule between the office and control networks usually exists because nobody has the port list. Rockwell publishes that list for each product and version; this article summarises how to divide zones and the most common ports.
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Rockwell Allen-Bradley PLC security: off the internet, RUN keyswitch, port 44818 blocked, firmware, backups
Exposed Rockwell PLCs are a real risk, but the basics go a long way. A summary of Rockwell and CISA advisories and SECURE-RM001: no internet exposure, EtherNet/IP blocked at the edge, zones, RUN keyswitch, CIP Security, firmware and backups.
Design, testing & operations
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What to check on a ControlLogix redundancy system before FAT: a checklist for 5580 and 5570
The chassis pair must match module by module, firmware must come from the same redundancy bundle, and there are five switchover tests and figures to measure (scan time, crossload, HMI data-loss time) before signing off FAT.
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FactoryTalk AssetCentre: automatic, versioned PLC/HMI program backup
AssetCentre stores PLC/HMI programs as versions, uploads them on a schedule and compares them with the master, and logs who changed what. This article summarises how to set up the system, the firewall ports and what to decide beforehand.
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SCADA upgrades: a chance to redo HMI and alarms to ISA-101 and ISA-18.2
Converting old screens to a new platform one-for-one carries every old habit along. ISA-101 and ISA-18.2 give an orderly approach: documents first, screens second; alarm only when the operator must act.
Fundamentals & comparisons
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What Is SCADA? How It Differs from PLC, HMI and DCS, Plant Architecture and How to Choose a Platform
SCADA is the supervisory and data acquisition layer above PLCs and RTUs. This guide compares it with PLC, HMI, DCS, historian and MES, shows a typical plant architecture and what to decide when choosing FactoryTalk, AVEVA, Ignition or N3uron.
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What Is an ICSS? Integrated Control and Safety Systems in Oil and Gas: PCS, SIS/ESD, F&G on Rockwell
An ICSS brings process control, ESD, F&G, operator stations and historian under one shared interface while keeping the SIS independent under IEC 61511. This guide covers the subsystems, ControlLogix + AADvance/Trusted architectures, integration points and what owners should specify.
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FactoryTalk View SE vs ME vs FactoryTalk Optix: Differences and Migration Checks
ME is a single-machine HMI, SE is HMI/SCADA from one workstation to a distributed system, and Optix is a newer platform licensed by feature tokens. A comparison of hardware, architecture, alarms, web access and licensing, plus what to check before migrating, from Rockwell documentation.