Description
Emerson 8104-AO-IP | 8-Channel 4–20mA Analog Output | PAC8000 I/O
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Emerson / MTL |
| Model | 8104-AO-IP |
| Product Family | PAC8000 / MTL8000 |
| Module Type | Analog Output |
| Number of Channels | 8 |
| Channel Configuration | Single-ended |
| Nominal Output | 4–20 mA |
| Full Signal Range | 1–23 mA |
| Resolution | 12 bit |
| Accuracy | ±0.25% of span |
| Output Compliance | 20 mA at 21.6 VDC into 700 Ω load |
| Open-Loop Detection | 0.7 ±0.25 mA threshold |
| Field Power | 24 VDC ±10%, bussed |
| Maximum Field-Power Current | 300 mA |
| Railbus 12 V Current | 100 mA typical / 150 mA maximum |
| Channel-to-Railbus Isolation | 100 VAC |
| Channel-to-Channel Isolation | None |
| Response Time | 25 ms maximum |
| Quiescent Current | 60 mA |
| Module Key Code | A4 |
| Module Width | 42 mm |
| Weight | Approximately 200 g |
The PAC8000 documentation lists the 8104-AO-IP specifically as an 8-channel, 4–20 mA analog output module. The detailed module specification identifies eight single-ended outputs, 12-bit resolution, ±0.25% span accuracy, 24 VDC bussed field power, and 25 ms maximum Railbus-command-to-output response.
Product Introduction
The Emerson 8104-AO-IP is an eight-channel analog output module for the modular remote I/O platform. It converts control data received through the Railbus into eight independent 4–20 mA output signals for proportional field devices. Typical loads include I/P converters, valve positioners, and remote analog indicators. The outputs are single-ended, with no isolation between channels, while the module provides 100 VAC isolation between the channels and Railbus.
The Emerson 8104-AO-IP requires 24 VDC bussed field power and supports a full output range of 1–23 mA around the nominal 4–20 mA operating range. Open-loop detection is provided on each channel, giving maintenance personnel a useful diagnostic indication when a current loop is interrupted.
8104-AO-IP
Application Scenarios & Field Pitfalls — The Engineer’s Perspective
Engineering Pain Point
A 4–20 mA output fault is not necessarily an I/O-module failure. A broken field cable, incorrect loop polarity, excessive load resistance, missing 24 VDC field power, or a failed I/P converter can all produce the same symptom at the control-system level. With the 8104-AO-IP, troubleshooting should separate the Railbus command, module power, output current, and field load before replacing the module.
Typical Applications
1. Control valve positioning
The 8104-AO-IP can provide proportional 4–20 mA commands to suitable valve positioners and related final control equipment.
2. I/P converter control
The documentation specifically identifies I/P converters as an application for this output module.
3. Remote analog indication
4–20 mA outputs can be used to drive compatible remote indicators and other analog receiving equipment.
4. Process-control output stations
Eight channels in one module allow multiple proportional control signals to be concentrated within a remote I/O station.
Technical Pitfalls
Check the load resistance.
The documented compliance specification is 20 mA at 21.6 VDC into a 700 Ω load. If the loop resistance is too high, the module may be unable to maintain the required current even though the electronics are functioning correctly.
Remember that the channels are not isolated from each other.
The module provides 100 VAC channel-to-Railbus isolation, but there is no isolation between output channels. Field devices with different grounding arrangements therefore require careful wiring review.
Verify the bussed field supply.
The 8104-AO-IP requires 24 VDC bussed field power, with a documented maximum field-power current of 300 mA. A missing field supply can affect several outputs simultaneously and may be mistaken for a multi-channel module failure.
Use the open-loop diagnostic correctly.
The specified open-loop detection threshold is 0.7 ±0.25 mA. A loop that is electrically marginal may therefore require examination of both the field wiring and receiving device rather than immediate module replacement.
Do not confuse it with 8102-HO-IP.
Both modules provide eight 4–20 mA outputs, but 8102-HO-IP includes HART, while 8104-AO-IP is the standard 4–20 mA analog output module. The HART requirement should therefore be checked before selecting a replacement.
Check the field terminal and mechanical keying.
The documented module key code is A4. Compatible field-terminal choices depend on the installation and hazardous-area requirements, so the existing carrier and terminal arrangement should be checked before replacement.
Consider the hazardous-area application.
The 8104-AO-IP has documented hazardous-area applications, but the module’s approval conditions depend on the complete system, field terminal, enclosure, wiring, and installation method. FM documentation specifies approved field-terminal combinations and installation conditions.
Related Products
- Emerson 8102-HO-IP — 8-channel 4–20 mA analog output with HART.
- Emerson 8103-AI-TX — 8-channel 4–20 mA analog input.
- Emerson 8101-HI-TX — 8-channel 4–20 mA analog input with HART.
- Emerson 8119-VI-05 — 8-channel 1–5 V analog input.
- Emerson 8132-AI-UN — isolated universal analog input supporting 4–20 mA, thermocouple, RTD, and voltage.
- Emerson 8204-AO-IS — 8-channel intrinsically safe 4–20 mA analog output.
- Emerson 8202-HO-IS — 8-channel intrinsically safe 4–20 mA analog output with HART.
- Emerson 8104-AO-IP compatible field terminals — terminal selection must match the installation and hazardous-area requirements.
- Emerson 8515-BI-PN — PROFINET Scanner module supporting the 8104-AO-IP in compatible configurations.
Procurement Note
When sourcing an 8104-AO-IP, match the exact catalog number and verify the 8-channel 4–20 mA architecture, 24 VDC bussed field power, A4 keying, field-terminal type, and required isolation arrangement. Do not substitute the HART-equipped 8102-HO-IP unless the control strategy and host configuration have been checked.
For used or surplus inventory, inspect the terminal interface, module keying, housing, and signs of overheating or field overvoltage. A meaningful functional test should exercise several channels with representative loop loads and confirm output current across the operating range rather than checking only for a nominal 4–20 mA signal.
Engineering classification: Emerson / MTL 8104-AO-IP — 8-channel, single-ended 4–20 mA analog output module with 12-bit resolution and 24 VDC bussed field power.
