Description
Product Introduction & Engineering Value
Field engineers frequently hit wall after wall trying to isolate sensitive control loops from ground loop noise in high-density panels. The Horner HE693DAC420 eliminates this issue by providing true 1500 VAC RMS channel-to-channel and channel-to-ground isolation directly inside the GE Fanuc Series 90-30 backplane architecture.
Converting digital values (0 to +32,000) from CPU %AQ registers into precision 0-20mA or 4-20mA current outputs, this module delivers stable current loop control for field actuators without requiring external signal isolators. Its configurable fault modes ensure your field equipment holds position or defaults safely during CPU stop events.
Technical Specifications
- Number of Channels: 4 isolated analog current outputs
- Output Signal Ranges: Software/config selected 4–20 mA or 0–20 mA
- Resolution: 14-bit (13 bits plus sign); 2.0 µA per bit in 4-20mA mode
- Isolation Rating: 1500 VAC (RMS) / ±2000 VDC channel-to-channel and channel-to-ground
- External Loop Power: Requires 3 to 32 VDC user loop supply
- Max Load Impedance: ≤ 1.1 kΩ @ 24 VDC loop voltage
- Backplane Power Consumption: 90 mA @ 5 VDC / 120 mA @ 24 VDC
- Power-Up Current Surge: 250 mA for 10 ms @ 5 VDC / 900 mA for 30 ms @ 24 VDC
- Linearity Error: ±0.10% Full Scale (4–20 mA mode)
- CPU Registers Occupied: 4 x %AQ registers
Field Application & The “Trench” Experience
During an emergency midnight callout at a municipal wastewater plant, an aging 90-30 rack lost control of a variable frequency drive speed reference due to a massive ground differential between the control building and the pump vault. The original non-isolated output card had blown its internal DAC driver stage. We swapped in an HE693DAC420, wired the 24V loop power, and instantly eliminated the 60 Hz hum on the current loop thanks to the 1500 VAC channel isolation.
Niche Application Scenarios:
- Chemical Dosing Valve Positioning: Precise 4-20mA stroke control for diaphragm metering pumps operating in high-noise VFD environments.
- Combustion Air Damper Control: Driving I/P transducers on large industrial boiler burner management systems.
- Marine Thruster Reference Lines: Isolated current loops running across long cable trays with variable ground potentials.
- HE693DAC420
- HE693DAC420
Transparency SOP: QA & Testing
To guarantee that our New Surplus and Refurbished inventory performs reliably in critical loops, every HE693DAC420 unit undergoes strict bench validation:
- Visual & ESD Inspection: Enclosure check, edge connector tab inspection, and thermal imaging during power-up.
- Backplane Current Draw Test: Verification of the 5 VDC and 24 VDC power draw to check for shorted internal power rails.
- Isolation High-Pot Testing: Applying high-voltage isolation tests across channels to verify the 1500 VAC RMS barrier.
- 4-Point Current Output Calibration: Loop calibration across 0 mA, 4 mA, 12 mA, and 20 mA using precision Fluke 773 meters into a 500 Ω load.
- CPU Fault Mode Simulation: Mode-switch test on a Series 90-30 test rack to ensure “Hold Last State” and “Default to 4mA/0mA” trigger properly when the CPU drops out of RUN mode.
The Veteran’s Tech Trap Guide
- ⚠️ External Loop Supply Required: A frequent mistake is assuming this card supplies loop power internally. It does not. You must supply 3–32 VDC (typically 24 VDC) to power the output loops, or your outputs will read 0 mA across the board.
- PRO TIP: Watch your scaling registers! The module expects integer values from 0 to +32,000 in the %AQ register. If your PLC code scales to 0–4095 or 0–32767, your field output current will be off by several milliamps.
- ⚠️ PLC STOP State Reaction: Double check software configuration regarding CPU mode transitions. If your application controls a critical cooling valve, ensure the channel is set to “Hold Last State” rather than “Default to 0mA” to prevent overheating during program updates.
Dynamic FAQ
Q: Does the HE693DAC420 require a special software configuration file in VersaPro or Proficy ME?
A: It configures seamlessly as an expansion 4-channel %AQ module within standard GE Fanuc Series 90-30 logic programming tools, though mode selection (0-20mA vs 4-20mA) and fault reactions are set via configuration parameters or software setups.
Q: Can I run this module without connecting external 24V loop power if I only need one channel?
A: No. The internal D/A converter circuitry on the field side relies on the external user loop supply (3–32 VDC) to drive current through the outputs.
Q: How do I know if I have a real New Surplus unit versus a cleaned-up pull?
A: Authentic New Surplus modules retain clean OEM board coating, pristine rear backplane contacts without insertion groove wear, and original Horner factory batch labels.
Q: What is the standard warranty on refurbished or new surplus units?
A: Every unit ships fully tested and backed by a 1-Year replacement warranty, covering full functional operation under standard plant conditions.
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