Description
Product Introduction
The GE Fanuc IC670ALG620 is a 4-channel analog output module engineered for GE’s modular Field Control distributed I/O platform. Designed to interface field actuators—such as control valve positioners, variable frequency drives (VFDs), and proportional dampers—with a central controller, this versatile card converts 12-bit digital logic commands into accurate current or voltage signals.
Mounting directly onto a Field Control Terminal Block (such as the IC670TBX001), the IC670ALG620 handles digital-to-analog conversion at the remote I/O drop. Each channel can be configured independently for either current loop (4–20 mA / 0–20 mA) or voltage range (0 to +10 V / -10 to +10 V) operation, providing flexible control over process equipment.
Key Technical Specifications
| Parameter | Specification |
| Manufacturer | GE Fanuc / Emerson |
| Part Number | IC670ALG620 |
| System Compatibility | GE Field Control Station (Bus Header required) |
| Associated Terminal Base | IC670TBX001 / IC670CHS001 |
| Number of Channels | 4 independently configurable outputs |
| Configurable Ranges | Current: 4 to 20 mA, 0 to 20 mA | Voltage: 0 to +10 VDC, -10 to +10 VDC |
| Resolution | 12 bits (1 part in 4096) |
| Update Rate | 1.0 ms for all 4 channels |
| Bus Power Consumption | 5 VDC @ 75 mA (from Field Control bus) |
| External User Power | 24 VDC nominal (20 to 30 VDC required for current loop outputs) |
| Output Load Resistance | Current: 0 to 850 ohms @ 24 VDC | Voltage: 2,000 ohms minimum load |
Application Scenarios & The “Trench” Experience
It’s 2:00 AM at an automated boiler plant. The main steam pressure control loop begins hunting erratically. The central PLC sends steady 4–20 mA positioning signals to the main fuel gas control valve, but channel 1 on the remote analog output card holds a flat 0 mA output. The DAC stage on the old IC670ALG620 card failed due to heat build-up inside the enclosure, locking the fuel valve in its fail-safe closed position and tripping the steam turbine.
Primary Industrial Applications
- Process Control Systems: Modulating Valve Positioners – Drives 4–20 mA I/P converters on steam, water, and gas control valves.
- Variable Frequency Drives (VFDs): Motor Speed Referencing – Sends 0–10 VDC or 4–20 mA speed reference signals to VFDs across pump skids and fan arrays.
- HVAC & Environmental Control: Air Handler Damper Control – Controls proportional dampers and chilled water valves in commercial HVAC loops.
- Chemical Batching Systems: Dosing Pump Speed Control – Regulates stroke rates on chemical injection pumps based on real-time pH and flow feedback.
Field Case Study
An ethanol production plant in Iowa experienced a channel failure on a Field Control drop governing its distillation feed valves. Instead of replacing the entire remote station—which would require replacing the Bus Header, pulling new network cables, and rewriting CPU I/O configuration files—the technicians swapped out the faulty module for a pre-tested surplus IC670ALG620. Because Field Control modules snap directly onto wiring bases without disturbing field cables, the new card was installed and driving valves in under 15 minutes.
IC670ALG620
IC670ALG620
IC670ALG620
Transparency SOP: Quality Assurance & Testing
Every IC670ALG620 module undergoes functional screening on active Field Control test rigs:
- Connector & Housing Inspection: Check of edge pins, casing snap latches, and internal PCB traces for signs of corrosion, thermal stress, or mechanical wear.
- Base Engagement Verification: Seating the card onto an active terminal base (IC670TBX001) linked to a Field Control Bus Header to confirm backplane communications and power initialization.
- 4-Channel Precision Output Audit: Driving test current (4.0 mA, 12.0 mA, 20.0 mA) and voltage (0 V, +5 V, +10 V, -10 V) references across all 4 channels, using calibrated digital multimeters to verify 12-bit DAC accuracy and linearity.
- Load Stability Testing: Running channels under full 850-ohm loop loads to verify output drive capability without thermal drift or voltage droop.
- ESD Packaging & Protection: Clearing configuration registers, placing the module inside an anti-static ESD shielding bag, and packing with custom foam cushioning.
The Veteran’s Tech Trap Guide (Crucial Value-Add)
⚠️ Trap 1: Check External 24 VDC Power Wiring!
While the Field Control backplane supplies 5 VDC logic power to run the module’s microprocessor, driving 4–20 mA current loops requires an external 24 VDC user supply wired to the terminal base. If your voltage outputs work but current channels read 0 mA, check your 24 VDC external power terminals first before replacing the card.
❗ Trap 2: Pay Attention to Output Mode Configuration.
Each channel can be set for voltage or current output, but this mode must be correctly configured in software (via Machine Edition or the Bus Header configuration file) AND wired according to the corresponding pins on the terminal base. Mismatches between software configuration and physical field wiring can prevent field actuators from responding.
⚠️ Trap 3: Watch Maximum Loop Load Resistance.
In 4–20 mA current mode, the maximum loop resistance the module can drive is 850 ohms at 24 VDC. Excessively long field wire runs combined with high-impedance I/P converters can exceed this limit, causing the output current to saturate before reaching full-scale 20 mA.
❗ Trap 4: Never Pull Module Casing Without Releasing Base Latches.
While Field Control allows module replacement, pulling the electronics casing off its terminal base without releasing the top and bottom snap latches can bend or snap the delicate connector pins linking the card to the backplane.
Frequently Asked Questions (FAQ for Conversion)
Q: Can I replace the without disconnecting field wiring?
A: Yes! Field Control separates the electronics module () from the terminal wiring base (IC670TBX001). You can unlatch and pull the top module straight off the base without unwiring any field terminal screws.
Q: What is the difference between and IC670ALG240?
A: The is an Analog Output module (sends control signals to field devices), whereas the IC670ALG240 is an Analog Input module (reads 4–20 mA signals from field transmitters).
Q: Can I mix voltage and current outputs on the same module?
A: Yes. Each of the 4 output channels can be independently configured in software for current (4–20 mA / 0–20 mA) or voltage (0 to +10 V / -10 to +10 V) ranges.
Q: Why choose pre-tested surplus modules over replacing the entire drop?
A: Upgrading a Field Control drop requires migrating network gateways, replacing wiring bases, redrawing panel schematics, and re-writing PLC program files. Dropping in a pre-tested replacement restores machine operation in minutes at a fraction of the cost.
Q: What warranty comes with this module?
A: Every module includes a full 12-month functional replacement warranty. If any channel or internal component experiences failures under normal operating conditions within 365 days, we replace it immediately.
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