Key Technical Specifications
| Parameter | Value |
|---|---|
| Channels | 8 single-ended |
| Signal Range | 4–20 mA (full range 1–23 mA) |
| Resolution | 16-bit |
| Accuracy | ±0.1% of span (across temperature) |
| Repeatability | 0.05% of span |
| Response Time | 27 ms max (4-20 mA); 0.75 sec/point (HART) |
| HART Support | HART passthrough, variable & status reporting |
| Fault Detection | Open circuit (<0.5 mA), short circuit (>23.5 mA) |
| Isolation | 100 V ac (any channel to rail bus); no channel-to-channel isolation |
| Bus Current Draw | 100 mA typical / 150 mA max (12V rail) |
| Field Power | 24 V DC ±10% bus field power required |
| Field Power Capacity | 300 mA max (2-wire TX); 60 mA max (4-wire TX) |
| FM Non-Incendive | Voc = 28.7 V; Isc = 33 mA; Ca = 0.17 μF; La = 11.0 mH |
| Module Width | 42 mm |
| Module Weight | 200 g |
| Module Key Code | A1 |
Product Introduction
I’ve pulled a lot of analog input cards out of racks over the years, and the ones that cause the most grief are the ones where someone assumed “8-channel 4-20 mA” meant they were all the same. The GE 8101-HI-TX-02 is a PAC8000 series analog input module — 8 single-ended channels, 16-bit resolution, HART passthrough built in. It reads standard 4-20 mA loops and also passes HART digital variables and diagnostics back to the controller, which means you can pull secondary process data and transmitter health status without running extra wiring.What makes this card worth keeping in your spare parts inventory is the combination of ±0.1% accuracy across temperature, 27 ms response time in standard analog mode, and FM non-incendive field wiring parameters per channel. That last point matters if you’re working in Class 1 Div 2 or Zone 2 hazardous areas — you need the right field terminal block (8601-FT-NI or 8603-FT-FU) to maintain that certification. One thing to keep in mind: there is no channel-to-channel isolation, only channel-to-rail-bus isolation at 100 V ac. If your application has ground loop potential between channels, plan your wiring accordingly.
Quality SOP & Tech Pitfalls
The Lab Report (Pre-Shipment Testing)Before this module ships to a live site, here’s what a proper check looks like:
- Visual inspection: Check the PCB for corrosion, bent pins on the backplane connector, cracked solder joints, and verify the module key code stamp reads “A1.”
- Backplane seating test: Seat the module on a compatible PAC8000 rail and confirm the controller recognizes it without fault flags.
- Loop simulation: Inject calibrated 4-20 mA signals into each channel and verify the rail bus reads within ±0.1% of span.
- HART passthrough verification: Connect a HART communicator or software and confirm variable and status reporting passes through correctly.
- Fault detection check: Simulate open-circuit (<0.5 mA) and short-circuit (>23.5 mA) conditions to confirm the module flags them properly.
- Insulation test: Verify 100 V ac isolation between channels and rail bus using a calibrated insulation tester.
- ESD-safe packaging: Bag and seal with anti-static materials before shipping.
The Engineer’s WarningHere’s where I’ve seen this module bite people:
- Forgetting the 24 V DC field power. This module needs 24 V DC ±10% bus field power to drive 2-wire transmitters. I’ve watched technicians seat the module, see it power up on the 12V rail, and then wonder why their 2-wire transmitters aren’t reading. The rail bus powers the module logic. The field power powers the loop. Two different supplies. Don’t mix them up.
- Ignoring the field terminal block selection. If you’re in a hazardous area and you grab the standard 8602-FT-ST terminal block instead of the non-incendive 8601-FT-NI, you’ve just voided your FM certification. The module itself is rated for non-incendive wiring, but only when paired with the correct terminal block.
Installation & Configuration Guide
- Pre-Installation
⚠️ Lock out and tag out all field power and rail bus power before touching the module.- Photograph the existing module’s position, wiring, and any DIP switch or jumper settings.
- Record the failing module’s serial number, revision, and firmware version from the controller’s hardware configuration.
- Confirm you have the correct field terminal block for your area classification (standard vs. non-incendive).
- Removal
- Label every field wire before disconnecting.
- Release the module from the PAC8000 rail using the proper extraction method — do not pry or force it.
- Inspect the backplane connector for bent pins or debris before proceeding.
- Installation
- Verify the module key code is A1 before seating. PAC8000 modules use keying to prevent wrong-module insertion.
- Align the module with the rail slot and press firmly until it seats fully.
- Reconnect field wiring to the correct terminal block, matching your photo from step 1.
- Confirm 24 V DC field power is connected and within ±10% tolerance.
- Power-On & Testing
- Energize the rail bus first, then field power.
- Check the controller’s hardware configuration screen — the module should appear without fault codes.
- Inject a known 4 mA signal and verify the controller reads 0% (or the configured engineering units low range).
- Inject 20 mA and verify full-scale reading.
- Test HART passthrough by connecting a HART communicator to one of the channels and confirming variable readback.
- Run a full loop check on all 8 channels before returning to production.
Compatible Replacement Models
| Compatibility Tier | Model / Guidance | Notes |
|---|---|---|
| ✅ Drop-in Replacement | 8101-HI-TX-02 (same part number, same A1 key code) | Only if firmware and controller configuration match |
| ⚠️ Software Compatible | 8101-HI-TX (base part, verify suffix) | May require controller hardware config update; confirm revision compatibility |
| ❌ Hardware Mod Required | Any non-PAC8000 GE I/O module | Do not attempt to adapt — different backplane, different protocol |
Frequently Asked Questions
Can I use this module with 2-wire and 4-wire transmitters on the same card?
Yes. The 8101-HI-TX-02 supports both 2-wire and 4-wire transmitter configurations. Just make sure your field power budget accounts for the difference — 2-wire transmitters draw up to 300 mA max from the 24 V field supply, while 4-wire transmitters draw up to 60 mA max.Does this module have channel-to-channel isolation?
No. It has 100 V ac isolation between any channel and the rail bus, but there is no isolation between individual channels. If your field devices share ground references that could create ground loops, you’ll need to address that in your wiring design.What happens if a field wire breaks?
The module detects open-circuit conditions when the loop current drops below 0.5 mA and flags it as a line fault. Same for short circuits — anything above 23.5 mA triggers a short-circuit fault. Both conditions should propagate to your controller’s alarm system if configured properly.Is the HART passthrough reliable for diagnostics?
It works. HART variables and status reports pass through to the controller, but remember the speed trade-off: HART mode runs at 0.75 seconds per channel, compared to 27 ms in standard 4-20 mA mode. If you’re using HART for diagnostics rather than primary process control, that latency is usually fine. If you’re trying to run HART as your primary control signal, rethink your strategy.What field terminal block do I need for hazardous areas?
For Class 1 Div 2 or Zone 2 installations, use the 8601-FT-NI (non-incendive) or 8603-FT-FU (non-incendive fused) terminal block. The standard 8602-FT-ST block does not carry the FM non-incendive certification.Can I hot-swap this module?
I wouldn’t recommend it. Power down the rail bus, remove the module, install the replacement, and then power back up. Hot-swapping PAC8000 I/O modules can cause bus glitches that affect other modules on the same rail. Take the extra two minutes to do it clean.
