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Phone: +86 16626708626Description
Key Technical Specifications
| Parameter | Value |
|---|---|
| Catalog Number | 1771-OFE2 (also listed as 1771-0FE2) |
| Module Type | Analog Output, Current (4–20 mA) |
| Number of Channels | 4 individually isolated outputs |
| Output Range | 4–20 mA per channel |
| Digital Resolution | 12-bit binary |
| Data Format | Natural binary or BCD scaling (±9999) |
| Isolation | 1000 V between channels and backplane |
| Chassis Compatibility | Any 1771 I/O chassis (not leftmost adapter slot) |
| Slot Width | Single slot |
| Backplane Power | ~1.5 A @ 5 V DC from chassis (module does not need external power) |
| Power Dissipation | ~7.9 W (≈26.9 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 | 2 LEDs (module status / fault) |
| Mounting | Rack-mount via 1771 chassis |
| Certifications | UL, CE, CSA (industrial use) |
Product Introduction
The Allen-Bradley 1771-OFE2 is a 4-channel, 4–20 mA analog output module for 1771 I/O chassis used with PLC-5 and compatible ControlLogix/SLC-500 style backplanes in legacy systems. It converts 12-bit binary or BCD values from the processor into isolated current signals for control valves, actuators, VFD speed references, and other process devices.
This unit is chosen for its channel isolation (1000 V), single-slot footprint, and straightforward block-transfer programming in PLC-5 environments. In field deployments, it holds up well in noisy panels when wired per OEM guidance and paired with a proper 1771-WC wiring arm.
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 steady or flashing | Module fault or config mismatch | ✅ High | Read PLC diagnostic buffer; try known-good slot | Replace module if fault persists in multiple slots |
| All channels read 0 mA or stuck | Block transfer not executing or data table wrong | ✅ Medium | Verify block transfer (BT) instructions and N-file addresses in ladder | Correct BT config; test with forced values |
| One channel out of range, others OK | Field wiring or load issue on that channel | ❌ Medium | Measure loop current with calibrated meter; check 24 V loop supply and load | Repair field loop; do not replace module yet |
| Channels drift or noisy output | Ground loops or poor shielding | ❌ Medium | Check shield grounding (single-point); isolate signal grounds per manual | Rewire per OEM grounding scheme; verify isolation |
| Intermittent output after chassis move | Backplane contact or keying issue | ✅ Medium | Reseat module; inspect keying band (10–12 / 26–28) and backplane pins | Clean/reseat; replace if backplane pins are damaged |
If you’re stuck, send photos of the module, wiring arm, and a short diagnostic log (PLC fault table + BT config). We’ll review it before you pull the part.
1771-OFE2
1771-OFE2
Frequently Asked Questions (FAQ)
Q: Is the 1771-OFE2 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 or transient outputs.
Q: What’s the difference between 1771-OFE1 and 1771-OFE2?
A: OFE1 is voltage output (multiple ranges via jumpers). OFE2 is current output only (4–20 mA) and has no per-channel range jumpers. Don’t substitute without verifying your field devices expect 4–20 mA.
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 uses block-transfer I/O with PLC-5 processors.
Q: Do I need to set jumpers for 4–20 mA on the 1771-OFE2?
A: No. The 1771- ships with configuration jumpers installed for current output. Unlike the OFE1, you do not set per-channel voltage jumpers on the .
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-?
A: Yes. As long as the replacement is the same catalog number (1771-) and your block-transfer addresses and data formats match, the existing ladder logic should work without changes.
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 loop power and load connections.
