Description
Product Introduction
The GE Fanuc IC693ALG391 is a 2-channel analog output card engineered for Series 90-30 PLC systems. It accepts 12-bit binary data from the CPU and converts it into proportional analog signals to drive control valves, variable frequency drives (VFDs), strip-chart recorders, and other analog actuators.
Unlike dedicated single-mode cards, the IC693ALG391 supports both voltage (0 to +10V, -10 to +10V) and current (4 to 20 mA, 0 to 20 mA) configurations. Each channel operates independently, offering maximum versatility for mixed-field output requirements in process control systems while maintaining full backplane isolation.
Key Technical Specifications
| Parameter | Specification |
| Number of Channels | 2 isolated analog outputs |
| Current Output Ranges | 0 to 20 mA, 4 to 20 mA |
| Voltage Output Ranges | 0 to +10 VDC, -10 to +10 VDC |
| Resolution | 12-bit (1 part in 4096) |
| Update Rate | 5 ms for both channels |
| External Power Requirement | 24 VDC external supply required for loop outputs |
| Current Loop Load Impedance | 0 to 850 ohms at 24 VDC |
| Voltage Load Impedance | 2000 ohms minimum (5 mA max current) |
| Accuracy at 25°C | ±0.1% of full scale (voltage), ±0.2% of full scale (current) |
| Isolation | 1500V RMS channel-to-backplane |
IC693ALG391
IC693ALG391
Application Scenarios & The “Trench” Experience
It was 3:45 AM during a critical batch cycle at a specialty chemical plant when a failed analog output module jammed a steam control valve shut. Temperature dropped rapidly in the main reactor, threatening to freeze an entire $120,000 batch into a solid gel block. The plant’s legacy controller dropped communication with the valve actuator due to a blown output stage on channel 1. The midnight shift needed a drop-in replacement card to restore loop control before the reactor went cold.
Application Scenarios
- Chemical Processing – Control Valve Positioning: Converts 4-20mA output commands from PID loops directly to pneumatic I/P positioners for precise steam and fluid flow control.
- Manufacturing – VFD Speed Control: Sends 0-10V or 4-20mA speed reference commands to motor drives across conveyor lines and high-speed mixers.
- Boiler & Combustion – Damper Actuation: Controls combustion air dampers using ±10V or 4-20mA positioning signals to optimize fuel-to-air ratios.
- Water Treatment – Dosing Pump Control: Regulates variable-speed metering pumps based on real-time pH and chlorine analytical feedback.
Field Case Study
A steel rolling mill in Pennsylvania experienced a sudden drive-trip fault traced back to channel drift on an aging IC693ALG391 card. The module was sending erratic 0-10V speed references to a main roll stand drive, causing strip-tension failures that snapped steel sheets mid-run. Downtime was racking up at $12,000 an hour. We dispatched a fully tested, pre-calibrated surplus IC693ALG391 from our warehouse via emergency courier. The site technician powered down the rack, swapped the card, verified the external 24V supply, and had the rolling mill running at full capacity before daybreak.
Transparency SOP: Quality Assurance & Testing
Every IC693ALG391 module undergoes rigorous physical and functional verification on active GE hardware before leaving our floor.
- Inbound Inspection: Detailed physical check for trace damage, backplane pin bends, broken terminal block latches, and OEM label authenticity.
- Live Backplane Testing: Slotted into a live GE Series 90-30 rack (IC693CHS397 baseplate with IC693CPU350) to verify immediate system detection and configuration handshake.
- Multi-Point Precision Calibration: Hooked up to a Fluke 789 ProcessMeter across both channels to verify output precision at 0%, 25%, 50%, 75%, and 100% across all voltage and current ranges.
- Load & Thermal Drift Test: Operating under full load (850-ohm loop resistor) for 4 hours inside a thermal test chamber to screen for component heat failure or signal drift.
- Anti-Static Pack & Seal: Cleared in software, wrapped in heavy-duty ESD shielding, and packed into custom impact-absorbing foam packaging.
The Veteran’s Tech Trap Guide
- ⚠️ External 24V DC Power Required: This module requires an external 24 VDC power supply connected to the terminal strip to drive current loops and voltage stages. If your external 24V supply drops out or isn’t wired to terminals 1 and 2, your analog outputs will sit dead at 0mA / 0V despite what the CPU logic displays.
- ❗ Never Pull Under Power: The Series 90-30 backplane is not hot-swappable. Pulling this card out while the rack is powered can cause an inductive spike that fries the backplane logic chip or trips the main rack power supply (IC693PWR330). Always drop rack power first.
- ⚠️ Mind the Ground Loops: When using current output mode, ensure your field device inputs are isolated or share a common ground reference with the PLC external 24V supply. Unisolated grounds will cause offset errors and erratic valve behavior.
- ❗ Terminal Wiring Differences (Voltage vs. Current): Voltage and current outputs use different terminal pins on the removable connector block! Check your pinout drawing before landing wires—landing a current loop on a voltage output terminal can burn out the output driver stage.
Frequently Asked Questions (FAQ for Conversion)
Q: Is the GE Fanuc IC693ALG391 hot-swappable?
A: No. Pulling or inserting this module while the baseplate power is turned on will cause backplane communication errors and risks permanent hardware damage. Always shut down power before swapping.
Q: Does this card require an external power supply to operate?
A: Yes. The relies on an external user-supplied 24 VDC power source wired to the terminal block to drive its output circuitry. Backplane power alone is not sufficient.
Q: Can I use one channel for 4-20mA and the other for 0-10V simultaneously?
A: Yes. Each of the 2 channels is independently configured in software (Proficy Machine Edition or Logicmaster 90) for either current or voltage operation.
Q: What is the difference between IC693ALG390 and ?
A: The is an upgraded version featuring improved isolation, higher output stability, and updated internal components over the older ALG390 series, while remaining a direct drop-in replacement.
Q: What warranty comes with this surplus card?
A: We provide a full 12-month replacement warranty on every . All inventory consists of genuine OEM units sourced from plant upgrades and surplus stock, thoroughly bench-tested on active Series 90-30 racks.
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