PLC Controller Repair and Service

Professional Programmable Logic Controller Service

PLC controllers (Programmable Logic Controller) are the brain of every industrial automation system. Their failure means production shutdown and serious financial losses. EFIXLAB offers comprehensive PLC service — from diagnostics and electronics repair to user-program recovery and system upgrades.

Supported PLC Controllers

Siemens SIMATIC

We repair the full range of Siemens controllers — from classic S5 to the latest S7-1500:

S7-1500 — CPU 1511, 1513, 1515, 1516, 1518 (CPU board repair, battery replacement, firmware updates)
S7-1200 — CPU 1211C, 1212C, 1214C, 1215C, 1217C (module regeneration, communication port repair)
S7-400 — CPU 412, 414, 416, 417 (memory replacement, backplane repair, program recovery)
S7-300 — CPU 312, 313, 314, 315, 316, 317, 319 (MPI/DP interface repair, capacitor replacement)
S7-200 — CPU 221, 222, 224, 226 (I/O module service, COM port repair)
S5 — CPU 922, 928, 948 (legacy systems, hard-to-find parts, upgrade to S7)
ET 200S/M/SP — distributed I/O modules (DI/DO/AI/AO module repair, power supply replacement)
LOGO! — micro PLC (input/output regeneration, display replacement)

Allen-Bradley / Rockwell Automation

ControlLogix — CPU 1756-L61, L62, L63, L71, L72, L73, L82, L83 (backplane and communication module repair)
CompactLogix — CPU 1769-L30, L32, L35, L36, L37 (processor and I/O regeneration)
MicroLogix — CPU 1400, 1100, 1200, 1500 (electronics repair, EEPROM replacement)
SLC 500 — CPU 5/03, 5/04, 5/05 (legacy systems, ladder logic program recovery)
PLC-5 — older platform service (PLC-5/20, 5/40, 5/80)
Flex I/O, Point I/O — distributed modules (DeviceNet, EtherNet/IP interface repair)

Mitsubishi Electric

MELSEC iQ-R — CPU R04, R08, R16, R32, R120 (motion control processor repair, battery replacement)
MELSEC iQ-F — CPU FX5U, FX5UC (module regeneration, Ethernet port repair)
MELSEC-Q — CPU Q02H, Q06H, Q13UDH, Q26UDH (backplane repair, special modules)
MELSEC-L — CPU L02, L06, L26 (compact PLC service)
FX Series — FX3U, FX3G, FX3S, FX2N, FX1N (electronics repair, output transistor replacement)

Schneider Electric

Modicon M580 — CPU BMEP58, BMEHxxx (Ethernet processor and redundancy repair)
Modicon M340 — CPU BMXPx (CPU board and I/O module regeneration)
Modicon Quantum — CPU 140CPU65, 140CPU67 (legacy systems)
Modicon Premium — TSX57, TSXP57 (older platform service)
Modicon M221, M241, M251 — compact PLC (port repair, memory replacement)

Omron

NJ/NX Series — NJ501, NJ301, NX102 (machine automation controller, EtherCAT master repair)
CJ2 Series — CJ2M, CJ2H (CPU, motion and network module regeneration)
CP1 Series — CP1E, CP1H, CP1L (compact PLC, input/output repair)
CS1 Series — CS1G, CS1H, CS1D (duplex systems, redundancy repair)

Other Manufacturers

ABB AC500 — CPU PM554, PM564, PM581, PM582 (Profibus and Ethernet module repair)
Bosch Rexroth — PLC IndraControl L, XM (motion controller repair)
B&R Automation — X20 PLC (POWERLINK processor regeneration)
Delta DVP — SS, SE, SV, EH series (economy PLC, module repair)
Beckhoff — CX embedded controllers (PC-based PLC controller repair)
Wago — PFC100, PFC200 (Linux-based controllers, I/O module repair)

What We Repair

Processor Modules (CPU)

PLC central units contain a microprocessor, program and data memory, and communication ports:

Surge damage — power circuit and voltage regulator replacement
Memory problems — EEPROM, Flash replacement, RAM backup battery swap
Communication port failures — RS232/RS485, MPI, Profibus, Ethernet regeneration
System errors — firmware reprogramming, watchdog repair
RTC clock problems — oscillator, crystal, battery replacement

I/O Modules

I/O modules are the PLC interface with sensors and actuators. Typical faults:

Digital inputs (DI) — burnt optoisolators, damaged RC filters
Digital outputs (DO) — blown transistors, burnt relays
Analog inputs (AI) — drifts, non-linearities, damaged ADC converters
Analog outputs (AO) — damaged DAC, 0–10 V / 4–20 mA output circuits
Counter / encoder modules — HSC and SSI interface problems

Communication Modules

Profibus DP/PA — master/slave interface and repeater regeneration
Profinet — Ethernet port and internal switch repair
EtherNet/IP, Modbus TCP — network controller replacement
DeviceNet, CANopen — CAN interface repair
AS-Interface — ASi master regeneration
Serial RS232/RS485 — converter and transceiver repair

Power Supply Modules

24 V DC power supplies for controllers and I/O modules
Redundant power supplies and UPS buffers
Built-in CPU power supply circuits
EMI filters and surge protection

Backplane & Rack Systems

Power and communication rail repair
Backplane connector replacement
Distribution circuit regeneration

Typical Failures & Symptoms

No Communication with PLC

If you cannot connect to the controller via a programmer:

Communication port damage — surge, short circuit, ESD
Processor failure — no initialization, frozen firmware
Cable / adapter issues — damaged USB-RS232 converter
Wrong communication settings — baud rate, parity, station address

Display Errors & Alarms

BUS ERROR / SF LED — backplane module failure, internal communication problems
BATTERY ALARM — dead battery, risk of program loss (SRAM)
PROG ERROR — program corruption, checksum error
I/O ERROR — no response from input/output modules
WATCHDOG ERROR — scan cycle hang

Input / Output Problems

Input not responding — burnt optoisolator, damaged input filter
Output not switching — blown transistor, burnt relay
False analog readings — drifts, interference, cold solder joints
Signal noise — shielding problems, damaged filters

Overheating

Power supply cooling fan failures
Blocked ventilation openings (dust, dirt)
Swollen capacitors from high temperature
Thermal problems in cabinets without air conditioning