Product Overview
When your process demands precise analog signal acquisition with high reliability, the ABB AI845 Analog Input Module delivers. Designed for single or redundant applications, this module provides 8 channels that accept 0...20 mA, 4...20 mA, 0...5 V, or 1...5 V DC unipolar single-ended inputs. Each channel can be individually configured as voltage or current when used with MTU TU844 or TU845; with other MTUs, all channels operate as voltage or current inputs uniformly.
Key Technical Specifications
- Resolution: 12-bit
- Input Impedance: >10 MΩ (voltage), 250 Ω (current)
- Isolation: Groupwise isolated from ground
- Input Filter Rise Time (0-90%): 290 ms
- Update Cycle Time: 10 ms
- Max Non-Destructive Input Voltage: 11 V DC
- Power Dissipation: 3.5 W
- Current Consumption: +5 V Modulebus: 100 mA; +24 V Modulebus: 50 mA; +24 V external: max 265 mA
The module features built-in current-limited transmitter supply per channel, supervised and current-limited for 2-wire or 3-wire HART transmitters. HART pass-through communication enables digital integration without compromising analog measurement.
Industry Applications
Process Control in Chemical Plants
In chemical processing, the AI845 monitors critical parameters like pressure, temperature, and flow via 4...20 mA loops. Its 0.1% max error and 50 ppm/°C temperature drift ensure stable readings even in harsh environments. Redundant operation eliminates single points of failure, reducing unplanned downtime.
Oil & Gas Pipeline Monitoring
For remote pipeline stations, the module’s 600-meter maximum field cable length allows flexible placement of transmitters. The groupwise isolation from ground protects against ground loops, while advanced diagnostics (module error, channel error, external power supply low) simplify troubleshooting.
Installation & Setup Guidance
Mount the AI845 on an S800 series I/O rack using compatible MTUs (e.g., TU810, TU812, TU814, TU818, TU830, TU833, TU835, TU838, TU844, TU845, TU854). Ensure proper keying code (CC) alignment. Connect field wiring per the terminal assignments in the user manual. For redundant configurations, install two modules and configure redundancy via the control system. Verify operating temperature range: 0 to +55 °C (+32 to +131 °F) – note that approvals are issued for +5 to +55 °C. For vertical mounting in compact MTU, max ambient temperature is 40 °C (104 °F).
Maintenance & Reliability
Periodically inspect front LEDs (Fault, Run, Warning) for status indication. The module performs self-supervision including analog readback, reference voltage, internal power supply, checksum, watchdog, and memory error checks. Internal channel errors (low pass filter, multiplexer, test channel) and external channel errors (external power supply low, transmitter power, external shunt) are reported. Follow manufacturer guidelines for cleaning – use only dry, low-pressure air to remove dust. No disassembly or contact cleaning is required.
Compatibility & Integration
The AI845 integrates seamlessly with ABB’s S800 I/O system and supports HART pass-through for digital communication with HART-enabled field devices. It is compatible with a wide range of MTUs listed above. The module carries CE mark, UL 61010-1, ATEX Zone 2, and marine certifications (BV, DNV, LR). EMC compliance with EN 61000-6-4 and EN 61000-6-2 ensures reliable operation in industrial environments.
Comparison with Similar Modules
| Feature | AI845 | AI830 | AI835 |
|---------|-------|-------|-------|
| Channels | 8 | 8 | 8 |
| Input Types | Voltage/Current (configurable) | Voltage/Current (fixed) | Voltage/Current (fixed) |
| HART Pass-through | Yes | No | Yes |
| Redundancy | Yes | No | Yes |
| Resolution | 12-bit | 12-bit | 12-bit |
| Isolation | Groupwise isolated | Groupwise isolated | Groupwise isolated |
Note: This comparison is based on typical ABB S800 series specifications. Verify exact specs for your model.
Selection Guide & Purchasing Advice
Before ordering, confirm your MTU compatibility and required input type. The AI845 (3BSE023675R1) is available at SpareTechPLC – your trusted source for industrial automation parts. We offer genuine ABB modules with fast shipping. Please verify current lifecycle status and availability with SpareTechPLC before ordering.
Troubleshooting & Common Issues
- No channel reading: Check field wiring, MTU connection, and module power. Verify transmitter supply voltage.
- Warning LED active: Review supervision status – possible external power supply low or transmitter power fault.
- Inaccurate readings: Ensure input filter settling time (290 ms) is respected. Check for ground loops – groupwise isolation helps but proper wiring is essential.
- HART communication failure: Confirm HART pass-through is enabled in configuration. Check cable length – max 600 meters.
Frequently Asked Questions
Q: Can the AI845 be used in redundant applications?
A: Yes, the AI845 supports redundant operation. Two modules can be configured for redundancy to increase system availability.
Q: What is the maximum cable length for field wiring?
A: The maximum field cable length is 600 meters (656 yards).
Q: Does the AI845 support HART protocol?
A: Yes, the module features HART pass-through communication, allowing digital data from HART-compatible transmitters to be transmitted to the control system.
Q: What is the resolution of the AI845?
A: The module has 12-bit resolution.
Q: What certifications does the AI845 have?
A: It carries CE mark, UL 61010-1, ATEX Zone 2, and marine certifications (BV, DNV, LR).
