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Phone: +86 16626708626Description
Key Technical Specifications
| Parameter | Value |
|---|---|
| Catalog Number | 1771-OX (also listed as 1771-0X) |
| Module Type | Power Contact Output (Relay) |
| Number of Outputs | 4 individually isolated, selectable NO/NC |
| Contact Configuration | Selectable Form A (NO) or Form B (NC) per output |
| Max AC Voltage | 0–250 V AC (inductive loads) |
| Max DC Voltage | 0–175 V DC |
| Max Continuous Current | 2 A @ 100 V AC (200 VA max per module) |
| Backplane Current | ~550 mA @ 5 V DC (all coils energized) |
| Chassis Compatibility | Any 1771 I/O chassis (not leftmost adapter slot) |
| Slot Width | Single slot |
| Power Dissipation | ~2.75 W (≈9.4 BTU/hr) |
| Operating Temperature | 0 to 60 °C (32 to 140 °F) |
| Humidity | 5–95% non-condensing |
| Field Wiring Arm | 1771-WC (or compatible 1771-WH variants) |
| Wiring Torque | 7–9 in-lb on wiring arm terminals |
| Indicators | 4 status LEDs (one per output) + module status |
| Mounting | Rack-mount via 1771 chassis; install within 30° of vertical |
| Relay Type | Mercury-wetted relay contacts |
| Max Interconnect Cable | 1000 ft (304.8 m) |
| Certifications | UL, CE, CSA (industrial use) |
Product Introduction
The Allen-Bradley 1771-OX is a 4-channel power contact output module for 1771 I/O chassis used with PLC-5 and compatible backplanes in legacy systems. It provides four isolated, selectable NO/NC relay outputs rated up to 250 V AC and 175 V DC for switching motors, solenoids, contactors, and other power loads.
This module is chosen for its high-voltage switching capability, selectable contact configuration, and simple ladder logic interface. In field panels, it’s commonly used where clean galvanic isolation and direct load switching are needed without adding external interposing relays.
1771-OX
1771-OX
Troubleshooting Quick Reference
| Symptom | Possible Cause | Relevance to this Part | Quick Check Method | Recommendation |
|---|---|---|---|---|
| No LEDs on power-up | Chassis power or backplane issue | ❌ Low | Measure 5 V DC at adjacent slots; check chassis PSU and fuses | Fix chassis power before swapping module |
| ERR/FAULT LED on | Module fault or internal relay coil issue | ✅ High | Read PLC diagnostic buffer; try known-good slot | Replace module if fault persists in multiple slots |
| One output stuck ON or OFF | Contact welded or coil failure | ✅ High | With power OFF, measure contact continuity; command output ON/OFF from PLC | Replace module if contacts are welded or coil open |
| Outputs not changing state | Program logic or wiring error | ❌ Medium | Force output in PLC; measure at wiring arm terminals | Correct ladder logic or wiring; verify common wiring |
| Chattering or intermittent output | Loose wiring or vibration affecting mercury-wetted relays | ✅ Medium | Inspect wiring arm torque; verify module is mounted within 30° of vertical | Re-seat and torque; re-mount per OEM vertical requirement |
| Multiple outputs failing together | Backplane power or common wiring issue | ❌ Medium | Measure backplane 5 V; check common terminal wiring and fuses | Repair backplane power or common wiring first |
If you’re stuck, send photos of the module, wiring arm, and a short diagnostic log (PLC fault table + forced output test). We’ll review it before you pull the part.
Frequently Asked Questions (FAQ)
Q: Is the 1771-OX hot-swappable?
A: No. The 1771 platform is not designed for hot-swap. Power down the chassis before inserting or removing the module to avoid backplane damage and unintended load switching.
Q: What’s the difference between 1771-OX and 1771-OW / 1771-OW16?
A: OX is a 4-channel power contact module with selectable NO/NC per output and higher voltage/current ratings. OW/OW16 are relay contact output modules with fixed NO contacts and different point counts. Don’t substitute without checking voltage, current, and contact configuration.
Q: Do I need to set jumpers for NO/NC on the 1771-OX?
A: Yes. The 1771-OX uses selectable configuration plugs to set each output as Form A (NO) or Form B (NC). Match the plug positions to your old module or the wiring diagram before installation.
Q: Will this work in my existing 1771 chassis with a PLC-5?
A: Yes, in any standard 1771 I/O chassis slot except the leftmost adapter slot. It draws power from the backplane and appears as standard digital outputs in the PLC-5 image table.
Q: What condition are these modules in, and why is pricing lower than factory?
A: We sell New Original (New Surplus) and Refurbished (tested) units. Pricing is lower because these are surplus or professionally refurbished, not current factory production. Each refurbished unit goes through live functional testing and comes with a 1-year warranty.
Q: Can I keep my existing program when swapping a failed 1771-OX?
A: Yes. As long as the replacement is the same catalog number (1771-OX) and your I/O addressing matches, the existing ladder logic should work without changes. Just verify the NO/NC plug settings match your application.
Q: What wiring arm do I need?
A: Use the 1771-WC (or compatible 1771-WH series) field wiring arm. Torque terminal screws to 7–9 in-lb and follow the OEM wiring diagram for your load and common connections.
