Description
3. Key Technical Specifications
| Parameter | Value |
|---|---|
| Input Channels | 1-16 selectable; single-ended only |
| Input Current Ranges | 0 to 20 mA, 4 to 20 mA, and 4 to 20 mA Enhanced (selectable per channel) |
| Calibration | 4 µA/count (4-20 mA) / 5 µA/count (0-20 mA and Enhanced) |
| Update Rate | 13 ms (all 16 channels) |
| Resolution at 4-20 mA | 4 µA (4 µA/bit) |
| Resolution at 0-20 mA | 5 µA (5 µA/bit) |
| Resolution at 4-20 mA Enhanced | 5 µA (5 µA/bit) |
| Absolute Accuracy | ±0.25% of full scale @ 25°C (77°F) |
| Absolute Accuracy (Operating Temp) | ±0.5% of full scale over specified range |
| Linearity | < 1 LSB (4-20 mA) / < 1 LSB from 100 µA to 20 mA (others) |
| Isolation | 250 VAC continuous; 1500 VAC for 1 minute (field to backplane) |
| Common Mode Voltage | 0 volts (single-ended) |
| Cross-Channel Rejection | > 80 dB from DC to 1 kHz |
| Input Impedance | 250 Ω |
| Input Low Pass Filter Response | 19 Hz |
| External Supply Voltage Range | 20 to 30 VDC |
| External Supply Voltage Ripple | 10% maximum |
| Internal Power Consumption | 120 mA from +5 VDC bus / 65 mA from +24 VDC external supply |
| Weight | 1.06 lbs (0.48 kg) |
IC693ALG223
4. Product Introduction
The IC693ALG223 is a high-density analog current input module for the GE Fanuc Series 90-30 PLC platform, designed to interface with industrial transmitters and instruments that output current loop signals. This module provides 16 single-ended input channels, each individually configurable for three current ranges: standard 4-20 mA, 0-20 mA for applications requiring zero-based signals, and 4-20 mA Enhanced for open-wire fault detection capability. Factory-calibrated for precision, the module delivers ±0.25% accuracy at room temperature with 12-bit resolution (4 µA on 4-20 mA range, 5 µA on 0-20 mA and Enhanced ranges).
The Enhanced range is particularly valuable for critical applications. In this mode, the module can detect open-circuit conditions on 4-20 mA loops by monitoring for currents below approximately 4 mA and triggering a low alarm. This live-zero detection enables early fault identification before process parameters drift out of control. Each channel supports configurable high and low alarm thresholds, providing real-time fault detection across all 16 inputs.
With 250Ω input impedance, the module provides the burden resistance required for standard 4-20 mA current loops. The 19 Hz low-pass filter helps suppress high-frequency noise common in industrial environments. Update rate of 13 ms for all 16 channels ensures responsive data acquisition for process control applications. LED indicators—MODULE OK and USER SUPPLY OK—provide at-a-glance status diagnostics. Configuration is handled through Logicmaster 90-30/20/Micro programming software or via CIMPLICITY Control configurator, with parameters stored in the PLC. The module uses %AI references for analog data and %I references for status and alarm information.
5. QA & Testing SOP
Our QC process for this 16-channel analog current input module follows a rigorous 5-step verification:
1. Incoming Inspection: We verify part numbers and revision levels against GE/Emerson datasheets. Physical inspection checks for corrosion, bent pins, counterfeit markings, or thermal damage on the terminal connector. We trace lot codes to confirm manufacturing origin and ensure firmware compatibility.
2. Live Testing: The module powers up in a Series 90-30 test rack with both +5 VDC backplane power and external +24 VDC supply connected. We inject calibrated current signals across all configured channels at 4 mA, 12 mA, and 20 mA for all three range configurations. A calibrated Fluke 773 milliamp clamp meter verifies readings within ±0.25% of expected values. We test Enhanced mode by simulating open-circuit conditions and confirming alarm triggers below 4 mA. All enabled channels are scanned simultaneously for 4 hours under full load to confirm stability.
3. Electrical Testing: Insulation resistance exceeds 10 MΩ between field side and logic side (measured at 500 VDC). We verify the 250Ω input impedance on each channel using a precision resistance meter. Cross-channel rejection is verified by injecting a 1 kHz signal on one channel and confirming no measurable interference on adjacent channels.
4. Firmware/Config Backup: We record the exact firmware version. Photo documentation captures the terminal block configuration and any jumper settings before testing begins. Configuration parameters are backed up for reference.
5. Final QC & Packaging: The module passes final visual inspection, receives a QC pass tag documenting measured values for all input points across all ranges, and ships in anti-static packaging. Each unit includes a test report verifying accuracy, resolution, and alarm functionality on all 16 channels.
IC693ALG223
6. Installation Pitfalls & Guide
❗ Missing External +24 VDC Supply
This module requires an external +24 VDC supply (20-30 VDC range, 10% max ripple) to power the current loops. It draws 65 mA from this supply in addition to the loop currents themselves. Without this supply, the USER SUPPLY OK LED will not illuminate and current inputs will not function. Verify your external 24 VDC supply can handle the additional 65 mA load plus all loop currents (max 16 × 20 mA = 320 mA, total ~385 mA).
❗ Forgetting 250Ω Burden When Using Two-Wire Transmitters
Two-wire 4-20 mA transmitters require loop power. The module’s 250Ω input impedance provides adequate burden for most applications, but verify the transmitter’s minimum operating voltage requirements. Long cable runs with high resistance may drop too much voltage, causing the transmitter to drop below 4 mA or fail entirely. Calculate total loop resistance and ensure transmitter receives sufficient voltage (typically 12-24 VDC).
❗ Not Using Enhanced Mode for Critical Loops
If your application relies on detecting broken wires or failed transmitters, configure the channel for 4-20 mA Enhanced mode and set an appropriate low alarm threshold (typically 3.6-3.8 mA). Standard 4-20 mA mode does not distinguish between 0 mA (open circuit) and 4 mA (zero scale). Enhanced mode provides live-zero detection for fault identification.
❗ Exceeding External Supply Current Capacity
With 16 channels at 20 mA each plus the 65 mA module overhead, your external +24 VDC supply must provide up to 385 mA. An undersized supply causes voltage sag and inaccurate readings. Verify your external supply capacity and add 20-30% margin for reliability. Consider dedicated 24 VDC supplies for high-channel-count installations.
❗ Mixing 4-20 mA and 0-20 mA Without Updating PLC Scaling
Ranges are configurable per channel, but your PLC program must apply appropriate scaling factors for each channel. A 4-20 mA channel scaling 0-32000 counts represents 4-20 mA, while a 0-20 mA channel scaling 0-32000 counts represents 0-20 mA. Using identical scaling for different ranges causes significant process measurement errors. Document and implement proper scaling in your PLC program.
4-Step Replacement Guide:
- Pre-install: Document the channel configuration (range type per channel, active channel count, and alarm thresholds). Photograph the terminal block wiring noting which transmitters connect to each channel. Verify the external 24 VDC supply capacity.
- Removal: Power down the rack and external 24 VDC supply. Disconnect the terminal block wiring. Remove the failed module.
- Install: Install the replacement module. Reconnect the terminal block according to the documented wiring scheme. Ensure shield connections are properly terminated to COM or GND.
- Power-on Test: Apply power. Verify both LEDs illuminate (MODULE OK and USER SUPPLY OK). Inject known test currents (4, 12, 20 mA) to each configured channel and verify %AI values match expected readings within tolerance. Test Enhanced mode alarm functionality by breaking the loop and confirming low alarm triggers.
7. FAQ
Q: Does this module support differential current inputs?
A: No. The IC693ALG223 only supports single-ended current inputs. All 16 channels share a common return (COM). If you need differential inputs for noise immunity or ground isolation, consider using voltage input modules with differential capability (such as IC693ALG222) and external current-to-voltage converters, or install isolation barriers on critical loops.
Q: What’s the difference between 4-20 mA and 4-20 mA Enhanced?
A: Both ranges measure 4-20 mA currents, but Enhanced mode includes open-wire fault detection. In Enhanced mode, you can configure a low alarm threshold (typically 3.6-3.8 mA). If the loop opens and current drops below 4 mA, the alarm triggers, alerting the PLC to a transmitter or wiring failure. Standard 4-20 mA mode cannot distinguish between 4 mA (process zero) and 0 mA (open circuit). Use Enhanced mode for critical loops where fault detection is required.
Q: Can I mix different current ranges on the same module?
A: Yes. Each of the 16 channels can be independently configured for 4-20 mA, 0-20 mA, or 4-20 mA Enhanced. However, your PLC program must apply different scaling factors for each range type. Document which channels use which ranges and implement appropriate scaling in your PLC logic.
Q: What happens if a current loop opens (wire breaks)?
A: In standard 4-20 mA or 0-20 mA modes, the module reads 0 mA. In 4-20 mA Enhanced mode with a properly configured low alarm (e.g., 3.6 mA), the module detects the open circuit when current drops below the alarm threshold and sets the corresponding %I alarm bit. The PLC can then trigger an alarm, switch to backup sensors, or initiate safe shutdown procedures.
Q: Does this module power two-wire transmitters?
A: Yes, but indirectly. The module provides a 250Ω input impedance for the loop. Two-wire transmitters require loop power from an external +24 VDC supply. The external supply (20-30 VDC range) powers both the transmitter and the module’s current measurement circuitry. Ensure your external supply provides adequate voltage after accounting for loop resistance and transmitter voltage drop.
Q: Is this module still manufactured?
A: The Series 90-30 platform is mature and has been discontinued by GE/Emerson. Most available units are New Surplus or refurbished stock. Verify firmware compatibility with your existing modules before installation.
Q: Will this module work in a Series 90-70 rack?
A: No. This unit is designed specifically for Series 90-30 backplanes. Mechanical and electrical interfaces differ between Series 90-30 and 90-70. You need Series 90-70 specific modules (IC697ALGxxx series) for 90-70 racks.
Q: What does the “LT” suffix mean?
A: The “LT” suffix (as in IC693ALG223LT) is not a GE/Emerson factory revision—it’s a value-added service from certain suppliers indicating the module has undergone additional low-temperature testing. Electrically, IC693ALG223 and IC693ALG223LT are the same module type. The LT version typically includes a premium charge for the additional testing service.
Q: How do I minimize noise on long cable runs?
A: Use twisted-pair shielded instrumentation cable for all current loop connections. Connect the shield to COM or GND at one end only (typically at the PLC module) to avoid ground loops. Avoid running current loop cables parallel to high-voltage power cables. If noise persists, consider the module’s 19 Hz filter which provides some noise rejection, or install additional signal conditioning or isolation barriers for critical loops.
Q: What is the maximum external supply voltage ripple?
A: The external +24 VDC supply should not exceed 10% ripple (approximately 2.4 VPP). Excessive ripple can cause measurement inaccuracies, especially on 4-20 mA Enhanced mode where the alarm thresholds are near the low end of the range. Use a well-regulated power supply with adequate filtering for best performance.
