ABB HAI805 8-Channel HART Analog Input Module
Product Overview
HAI805 is an 8-channel HART analog input module of ABB Symphony Plus DCS SD series. It is mainly applied in power generation and water treatment industries to realize data interaction between Symphony Plus controllers and HART protocol intelligent field devices. The matching output module of the same series is HAO805. More than 6,500 sets of Symphony series DCS have been put into operation worldwide, among which over 4,500 sets serve power generation and water sectors. Following ABB’s "Evolve, Don’t Replace" philosophy, it supports backward-compatible system upgrades.
The module acquires primary 4‑20 mA analog signals and reads secondary, tertiary and quaternary HART digital variables. Unlike most modules that share one HART modem for all channels, each channel is equipped with an independent HART Modem. The refresh time of HART multi-variables is less than 1 second. Secondary variables can directly participate in real-time control logic of the controller instead of only being displayed on HMI screens. This improves the reliability of process control, reduces the quantity of field instruments and cuts overall project investment.
The hardware is equipped with STOP/RESET reset button and RUN/FAULT indicator lights. The module comes with detachable screw terminal blocks and supports hot swapping. With fiber repeaters adopted for I/O substations, the maximum distance from the controller can reach 3 km.
Key Specifications
- Channel Specification: 8-channel 4‑20 mA analog input, supports HART5/HART7
- Hardware Architecture: Independent HART modem per channel, excellent signal isolation and fast response
- Data Capability: Primary 4‑20mA variable plus secondary / tertiary / quaternary HART variables; multi-variables available for control calculation, screen display and alarm
- Refresh Rate: Update of secondary and higher HART digital variables ＜1s; full-channel scan of primary analog variable approx. 100ms
- Device Management: Based on S+ Engineering platform, DTM technology enables configuration, commissioning, diagnostic maintenance of HART instruments without extra handheld communicators
- Communication: HN800 redundant I/O bus; maximum transmission distance of 3km via fiber repeaters
- Operating Conditions: IP20, DIN rail mounting inside cabinet, operating temperature 0~+55℃
List of Supporting Products
- HAI805 cannot work independently and must rely on the complete Symphony Plus SD series subsystem.
Mandatory Hardware
| Model | Description |
| HPC800 | Symphony Plus controller, the only compatible controller for HAI805, supports redundant configuration |
| HN800 | Realizes HN800 redundant bus communication between controller and SD I/O modules; HN800 cables are also used for inter-cabinet cascading |
| HN811 | Termination resistor at the physical bus end of HN800 bus; must be installed at both ends of the whole bus to prevent communication packet loss |
| SD Series I/O Rack Backplane | Mounting base for HAI805, provides power supply and internal bus; the module has built-in terminal blocks with no extra terminal board required |
Co-Rack Compatible Modules
HAO805: 8-channel HART analog output module for HART valve positioners and smart actuators, can be deployed together with HAI805; each channel also equipped with independent HART Modem.
SD series standard I/O (AI/AO/DI/DO): Can share the same rack. Standard I/O for ordinary measurement points while HAI805/HAO805 for HART smart measurement points.
Long-Distance Extension Accessories
HN800 dedicated communication cable: Copper connection between controller cabinet and I/O substation;
HN8xx fiber repeater: Used in pairs, converts HN800 electrical signal to optical signal to realize remote I/O deployment up to 3km.
Power Supply, Installation & Field Auxiliaries
Rack 24VDC industrial power supply, redundancy recommended (supplies power to I/O rack; transmitter loop power is supplied by local 24V source instead of the module);
DIN rail: For SD rack cabinet mounting;
Shielded twisted pair cable: For HART/4‑20mA field loop, shield single-ended grounding.
Software Accessories
S+ Engineering (Composer): Logic configuration, module setup and HART channel parameter setting;
Instrument vendor DTM files: Imported into engineering software for full parameter configuration of HART instruments; only general variables can be read without DTM;
S+ Operations HMI software: Variable display, alarm and equipment diagnostic monitoring.
Incompatible Devices
Not compatible with 800xA system S800 I/O backplanes and modules;
Old non-Plus Symphony legacy backplanes and communication cards cannot directly work with HAI805;
HN800 bus cannot connect to ordinary RS485 converters; only ABB original supporting communication components are allowed.
Selection Guide
Recommended Application Scenarios for HAI805
HART smart transmitters deployed, multi-variable reading and instrument fault diagnosis required;
HART secondary digital variables need to participate in DCS real-time closed-loop control (not only HMI display);
Direct commissioning of HART instruments inside DCS engineering software to reduce field handheld communicators;
New or retrofit Symphony Plus projects with remotely distributed I/O substations.
Not Recommended Scenarios for HAI805
All field transmitters are conventional non-HART 4‑20mA types; standard AI modules are preferred for cost saving;
Non-HPC800 controller (HAI805 only supports Symphony Plus HN800 bus);
Only 4‑20mA acquisition required with no HART digital information utilized; module advantages cannot be leveraged.
Typical Complete Solutions
1. Local I/O Station: HPC800 + HN800 Communication Module + SD Rack + HAI805 + HAO805 + HN811 + S+Engineering
2. Remote I/O Station: HPC800+HN800 + Near-end Fiber Repeater + Optical Fiber + Far-end Fiber Repeater + SD Rack (HAI805)+HN811
Engineering Selection & Operation Notes
System Compatibility: Only compatible with HPC800 controller. Legacy Symphony system upgrade requires full replacement of controller and HN800 bus; old I/O backplanes cannot be directly replaced.
Bus Requirements: HN811 termination modules must be fitted at both ends of HN800 bus; original fiber repeaters are required for long-distance applications with maximum 3 km limit.
Loop Impedance: Total HART loop impedance must stay within 230‑600Ω; HAI805 input impedance is 250Ω. Abnormal impedance may result in normal 4‑20mA reading but HART digital communication packet loss.
Isolation: The module is group-isolated with no channel-to-channel isolation. Isolation between different field instruments shall be realized on site.
Software Logic: Secondary / tertiary / quaternary HART variables will not be uploaded automatically and must be explicitly called in controller function block programs. Sampling cycles differ between primary analog variables and HART digital variables; time offset shall be considered in control logic.
Field Commissioning: As HART master, HAI805 does not recommend parallel connection of handheld communicator on live loop; temporary connection for communicator commissioning. Shielded twisted pair cable with single-ended grounding for interference suppression.
Ambient Conditions: IP20 for DIN rail mounting inside control cabinet only, not for direct outdoor use; module hot swap supported.
Quick Selection Checklist
- Controller model HPC800 with HN800 redundant bus configured
- Field instruments support HART protocol, loop impedance calculated within 230‑600Ω
- Confirm project requirement for HART multi-variables in control logic or instrument maintenance via DCS
- Evaluate fiber repeaters for remote I/O substation and confirm 3km maximum distance limit
FAQ
Q1: Can HAI805 be used in ABB 800xA S800 I/O system?
A: No. HAI805 belongs to Symphony Plus SD series module, only compatible with HPC800 controller and HN800 bus. It is completely incompatible with 800xA S800 hardware and protocol.
Q2: 4‑20mA measurement is normal but secondary HART variables cannot be read. What are the possible causes?
A: ① Total loop impedance out of 230‑600Ω range;
② Secondary variables not explicitly called in program, variables will not upload automatically;
③ Field signal cable interference;
④ Parallel HART communicator on loop causing master conflict.
Q3: Is HN811 termination module mandatory for HN800 bus?
A: HN811 must be installed at both physical ends of the whole HN800 bus. Missing termination resistor causes signal reflection, resulting in unstable communication and occasional module offline packet loss.
Q4: Is there electrical isolation between HAI805 channels?
A: 8 channels are group-isolated without isolation channel to channel. Isolation between different instruments shall be implemented on site.
Q5: What happens if instrument DTM files are unavailable for HAI805?
A: Only general HART variables can be read. Private instrument parameters are inaccessible, and full transmitter configuration, parameter tuning and equipment maintenance cannot be completed inside S+ Engineering software.
Q6: Are refresh cycles of secondary HART variables consistent with primary 4‑20mA variables?
A: Inconsistent. Secondary HART digital variables update within ＜1s while full-channel scan of primary analog variable is approx. 100ms. Time difference must be considered when building control logic.
Q7: Does HAI805 support hot swapping? Is transmitter loop power supplied by the module?
A: The module supports hot swap. The module only supplies power to itself and does not provide 24V loop power for field transmitters; transmitters need external power supply.
Q8: All field transmitters are conventional non-HART 4‑20mA types. Should HAI805 be selected?
A: Not recommended. SD series standard AI modules are preferred for cost saving. HAI805’s HART hardware advantages cannot be utilized.
