TO MITSUBISHI FX5U: I/O MAP (PNP SOURCE, X0/X1/X2)
Quick answer: FX5U X inputs are ordinary inputs. Use a compatible safety device for the OSSD pair, any required EDM and the machine reset function. The X0–X3 map below is for independent status copies and event logging; it cannot establish a performance level or authorize restart. Verify the exact CPU input wiring and the complete safety circuit before commissioning.
Content updated: .
Diagnostic mapping example. Standardize how status from a safety light curtain’s OSSD1/OSSD2, EDM, and RESET are represented by independent diagnostic copies on MITSUBISHI FX5U digital inputs (PNP sourcing example). Includes a illustrative I/O list, naming rules, sample program (ST/Ladder-style), and commissioning checklist.
NAMING CONVENTION
| TAG | MEANING | NOTES |
|---|---|---|
LC_OSSD_CH_A | NON-SAFETY CHANNEL A STATUS COPY | MAP → X0 (PNP) |
LC_OSSD_CH_B | NON-SAFETY CHANNEL B STATUS COPY | MAP → X1 (PNP) |
LC_EDM_FB | CONTROLLER FEEDBACK-READY STATUS COPY | MAP → X2 (PNP) |
LC_RST_BTN | RESET-BUTTON INDICATION | MAP → X3 (LOGGING EVENT ONLY) |
LC_STATUS_OK | DERIVED “OK” STATE | INTERNAL BIT M100 |
LC_RESET_EVENT | RESET EVENT FOR LOGGING | INTERNAL BIT M101 |
POLARITY RULE: FOR PNP SOURCING, THE FX5U INPUT COMMON S/S = 0V, AND SENSOR OUTPUTS SOURCE +24V INTO X-INPUTS.
PNP WIRING OVERVIEW (TEXT DIAGRAM)
Start with the installation and wiring sequence to separate the protective circuit from PLC diagnostics. For the feedback portion, see series NC EDM feedback examples.
SAFETY PATH — use the exact device manuals
OSSD1 + OSSD2 -> compatible safety relay/controller inputs
K1 mirror NC -> K2 mirror NC -> rated EDM input (if supported)
RESET -> safety device reset input (if required)
Safety outputs -> validated final switching devices
ORDINARY FX5U — diagnostic copies only, where provided
Channel A status -> X0
Channel B status -> X1
Controller feedback-ready status -> X2
Independent reset-button indication -> X3
PNP input reference: S/S -> 0 V; confirm exact CPU manual
Never substitute X0/X1/X2 or PLC logic for the safety path.
No DA31 or DQSRN terminal/function compatibility is implied.- ROUTE OSSD CHANNELS AND SELECT CABLE/PROTECTION AS SPECIFIED BY THE SENSOR AND SAFETY CONTROLLER MANUALS.
- EDM USES SERIES NC CONTACTS OF K1/K2 BACK TO DOCUMENTED EDM INPUT ON THE SAFETY DEVICE.
- WHERE MANUAL RESET IS REQUIRED, USE THE MONITORED RESET FUNCTION SPECIFIED BY THE SAFETY DEVICE MANUAL.
- KEEP SIGNALS AND POWER ROUTING SEPARATED AS REQUIRED BY THE INSTALLATION MANUAL AND EMC DESIGN.
I/O MAP (COPY-READY)
| VARIABLE | FX5U ADDRESS | SOURCE | PURPOSE | REMARKS |
|---|---|---|---|---|
LC_OSSD_CH_A | X0 | Channel A status copy | DIAGNOSTIC CHANNEL A | PNP (S/S=0V) |
LC_OSSD_CH_B | X1 | Channel B status copy | DIAGNOSTIC CHANNEL B | DISPLAY ONLY |
LC_EDM_FB | X2 | Controller status output | FEEDBACK STATUS ONLY | SAFETY DEVICE CONTROLS RESET |
LC_RST_BTN | X3 | PUSHBUTTON | RESET-BUTTON INDICATION | EVENT LOG ONLY — NOT RESET PERMISSION |
LC_STATUS_OK | M100 | LOGIC | CHANNEL STATUS DISPLAY | DERIVED |
LC_RESET_EVENT | M101 | LOGIC | DIAGNOSTIC EVENT | ONE-SCAN LOG EVENT |
SAMPLE PROGRAM (ST-STYLE, FX5U)
// Diagnostic pseudocode; declare tags in the engineering project.
// X0/X1/X2 are independent status outputs from the safety system.
M100 := X0 AND X1; // HMI channel-status indication
M102 := X2; // HMI feedback-ready indication
M101 := X3 AND NOT RST_PREV; // one-scan event for a reset log
RST_PREV := X3;
// No safety output, contactor command or restart permission.
// Raw NC EDM feedback changes with contactor state;
// do not AND it with OSSD signals to create a safety enable.THIS PSEUDOCODE ONLY DISPLAYS STATUS AND LOGS A BUTTON EVENT. RESET TIMING AND RESTART INHIBITION BELONG TO THE VALIDATED SAFETY SYSTEM.
COMMISSIONING & SELF-TEST
- POLARITY: VERIFY S/S=0V FOR PNP; CHECK 24 V/0 V AND PE.
- CHANNEL COHERENCE: BLOCK/RELEASE BEAMS — VERIFY THE RATED DEVICE DETECTS CHANNEL FAULTS; X0/X1 PROVIDE DISPLAY INFORMATION ONLY.
- EDM: WITH HAZARDS SECURED, USE THE MANUFACTURER'S APPROVED FEEDBACK-FAULT TEST; DO NOT MECHANICALLY HOLD LIVE CONTACTORS.
- RESET: VERIFY THE CONFIGURED RESET AND RESTART BEHAVIOR AGAINST THE MACHINE RISK ASSESSMENT.
- RECORDS: ARCHIVE I/O LIST, ISO 13855 CALCULATION, WAVEFORMS/LEVELS.
SELF-TEST RECORD (CSV COPY)
Item,Test,Expected,Actual,Result,Notes
1,Status indication,PLC display follows documented auxiliary signals,,,
2,Protective stop,Rated safety path reaches specified safe state,,,
3,Feedback fault test,Approved procedure inhibits restart,,,
4,Reset behavior,Matches validated machine reset requirements,,,
5,PLC diagnostic failure,Safety path remains effective,,,
COMMON ERRORS & FIXES
| MISTAKE | SYMPTOM | FIX |
|---|---|---|
| UNVERIFIED OSSD LOAD OR WIRING | TEST-PULSE OR FAULT-DETECTION MISMATCH | FOLLOW BOTH DEVICE MANUALS |
| EDM LOOP OMITTED | RESET POSSIBLE WITH WELDED CONTACTOR | SERIES MIRROR NC TO DOCUMENTED RATED EDM INPUT |
| RESET HELD CONTINUOUSLY | UNINTENDED RESTARTS | VALIDATE RESET IN THE SAFETY DEVICE |
| MIXED PNP/NPN ON SAME COMMON | INPUTS STUCK ON/OFF | UNIFY POLARITY; SEGREGATE COMMONS |
FAQ
WHY PNP INSTEAD OF NPN?
INDUSTRY INTEROPERABILITY AND DIAGNOSTIC CLARITY. FOR THIS SUPPORTED PNP DIAGNOSTIC EXAMPLE, USE S/S=0VAS SHOWN IN THE EXACT CPU MANUAL. NPN REQUIRES A SUPPORTED INPUT CONFIGURATION AND MATCHING AUXILIARY SIGNAL. THIS DOES NOT SPECIFY THE OSSD SAFETY WIRING.
CAN THE PLC CUT THE SAFETY CIRCUIT?
NO. SAFETY STOP IS PERFORMED BY A SAFETY RELAY/CONTROLLER DRIVING K1/K2. PLC HANDLES STATUS AND DIAGNOSTIC EVENTS ONLY.
HOW DO I LOG RESET ATTEMPTS?
CREATE A ONE-SHOT COUNTER ON THE RISING EDGE OF X3 (RESET-BUTTON INDICATION) AND STORE TIMESTAMPS TO A RING BUFFER. THIS RECORD DOES NOT AUTHORIZE RESET OR PROVE THAT A SAFE RESTART OCCURRED.
Manufacturer reference
Mitsubishi Electric FX5 hardware manual: check the CPU-specific input diagram and external safety-circuit requirements. Any separate safety extension requires its own supported configuration and validation.
Frequently Asked Questions
How do I map a safety light curtain to a Mitsubishi FX5U?
Connect the OSSD pair to the compatible inputs of a documented safety relay or safety controller. The ordinary FX5U X0 and X1 map here uses independent status copies, X2 is feedback-ready indication and X3 is reset-button indication. These diagnostic inputs do not perform the stop, EDM or restart-permission function.
Should I wire PNP source or NPN sink on the FX5U?
Check the exact FX5U CPU input diagram. For the supported PNP diagnostic example, S/S is referenced to 0 V and the independent status output supplies a positive input signal. NPN wiring requires a supported configuration and matching signal type. Do not rewire the safety outputs based on this ordinary-input example.
Can the FX5U provide the safety function on its own?
A standard FX5U is not a safety PLC. A documented safety relay or controller must implement the validated protective function independently of this diagnostic example, with suitable final switching elements. The FX5U may display status and log events, not authorize a safety reset or restart.
What should the I/O naming convention be?
Label X0 and X1 as independent channel-status copies, X2 as feedback-ready status and X3 as reset-button indication. Existing LC_OSSD and LC_EDM tag names in the example refer only to these diagnostic copies; record their actual auxiliary source and do not mistake them for the safety wiring.
How do I confirm the setup during commissioning?
Validate the safety path using the machine and device procedures, including stopping performance, required feedback and fault response, restart prevention and approved test pieces. Check OSSD test-pulse compatibility at the rated receiving device. Verify that PLC diagnostic faults cannot defeat protection and keep the recorded results.