ABB AI835 3BSE008520R1 Analog Input 8 ch

I. Product Overview

ABB AI835 3BSE008520R1 is an analog input module that belongs to the I/O component family of the AC 800M series distributed control system (DCS). Specifically designed for the acquisition of continuously changing physical quantities in industrial processes, it is widely used in fields such as electric power, petrochemicals, metallurgy, building materials, and pharmaceuticals. Its core function is to collect, in real time, the continuous electrical signals output by on-site analog sensors (e.g., temperature sensors, pressure sensors, level sensors, flow sensors, vibration sensors). After undergoing signal isolation, noise filtering, signal amplification, and high-precision digital conversion, the standardized digital signals are transmitted to the AC 800M controller. It provides accurate and reliable analog data support for core control logics such as equipment operation status monitoring, process closed-loop control, process parameter adjustment, and fault prediction, serving as a key analog signal acquisition component that connects the on-site sensing layer and the control layer in industrial control systems.

This module adopts the standard modular architecture of the AC 800M series, featuring strong system compatibility and expandability. It can be directly inserted into compatible slots of standard I/O racks (such as CI854, CI855, CI856) and achieves high-speed communication with the controller via fieldbuses like PROFIBUS DP or EtherNet/IP. Adhering to industrial-grade high-reliability design standards, it incorporates designs such as multiple electromagnetic interference suppression, wide-temperature operating range optimization, and redundant configuration support, enabling stable adaptation to harsh industrial environments with high temperatures, heavy dust, strong vibrations, and intense electromagnetic interference. Relying on ABB's dedicated high-precision signal processing technology and adaptive calibration algorithm, it ensures the real-time performance and accuracy of analog signal acquisition, making it a core analog input component for building highly reliable industrial process control systems.

II. Technical Specifications

III. Functional Features

• Seamless Integration with AC 800M System, Efficient Deployment: The module adopts the unified hardware interface and communication protocol of the AC 800M series. It can be directly inserted into any compatible slot of standard I/O racks, enabling "plug-and-play" integration without the need for additional adapters, custom drivers, or jumper adjustments. It conducts high-speed data interaction with AC 800M controllers (e.g., PM864, PM866, PM867) via the I/O rack bus, with a total delay of ≤1ms for 8-channel parallel sampling, meeting the timing requirements of high-precision process closed-loop control. It fully supports ABB Control Builder M configuration software, allowing users to configure signal types, calibrate ranges, set filter parameters, define alarm thresholds, and perform linearization corrections for each channel through a graphical interface. It seamlessly links with the system's control logic, monitoring interface, and historical data recording, significantly shortening the system commissioning cycle.

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• Multi-Type Signal Compatibility, Wide Application Adaptability: It integrates 8 independent isolated input channels, and each channel can be independently configured via software into four signal types: voltage, current, thermocouple, and RTD, compatible with over 90% of mainstream analog sensors in industrial sites. For voltage/current signals, the module has a built-in Programmable Gain Amplifier (PGA) that can adaptively adjust to signals of different ranges, supporting common signals such as 0~10VDC and 4~20mA without hardware replacement. For thermocouple signals, it integrates a high-precision cold-junction compensation circuit, which uses a built-in high-precision temperature sensor to collect the module's ambient temperature and perform compensation via a compensation algorithm, achieving a compensation accuracy of ±0.3℃ without the need for external compensation modules. For RTD signals, it adopts a constant current source excitation method to effectively reduce the impact of lead resistance and contact resistance on measurement accuracy, supporting 3-wire and 4-wire wiring to improve temperature measurement stability. This multi-type adaptability allows it to be widely used in diverse scenarios such as boiler steam pressure monitoring, reactor temperature acquisition, tank level detection, and pipeline medium flow metering, reducing the procurement cost of dedicated modules.

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• High-Precision Acquisition Design, Accurate and Reliable Data: It adopts a 24-bit high-precision A/D conversion chip combined with a differential input architecture to achieve low-noise and high-resolution signal acquisition. The measurement accuracy of voltage/current signals reaches ±0.01% full scale, enabling accurate capture of tiny signal fluctuations (e.g., a 0.0004mA change in 4~20mA signals). Equipped with an adaptive digital filtering algorithm, it can automatically adjust the filtering strength according to signal noise characteristics and sampling rate—completely suppressing 50Hz/60Hz power frequency interference at a low sampling rate of 10 SPS, while still ensuring signal fidelity at a high sampling rate of 1000 SPS, thus guaranteeing the accuracy of dynamic signal acquisition. It supports single-point calibration, multi-point linear calibration, and temperature drift compensation functions. On-site calibration can be completed via Control Builder M software, and the post-calibration error can be controlled within ±0.005% full scale, meeting the requirements of metrological-grade monitoring.

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• Multiple Isolation and Anti-Interference, Adaptation to Harsh Environments: It adopts a triple electrical isolation design: "channel-channel", "channel-backplane", and "power supply-backplane", with isolation voltages of 1000VAC/1min (between channels), 2500VAC/1min (between channels and backplane), and 2000VAC/1min (between power supply and backplane) respectively. This effectively blocks interference from on-site ground loops, power fluctuations, and equipment electromagnetic radiation on signal acquisition. Each channel is equipped with an RC hardware filter circuit and a TVS surge suppression component, which can filter high-frequency noise below 100kHz and withstand transient surge impacts of ±2kV to protect internal circuits from damage. Compliant with IEC 61000-4 series electromagnetic interference immunity tests, it achieves RF interference suppression of ≥45dB in high-interference environments such as high-voltage motors, frequency converters, and welding machines, ensuring the stability and accuracy of signal acquisition and adapting to various harsh industrial scenarios.

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• Configurable Sampling Rate, Flexible Dynamic Response: It supports software-configurable sampling rates in a wide range of 10~1000 SPS. The maximum sampling rate of 1000 SPS per channel can meet the needs of dynamic process monitoring (e.g., pressure surge monitoring during steam turbine start-stop, rapid temperature change monitoring in chemical reactors). The 8-channel parallel sampling design ensures synchronous acquisition of multiple parameters, with a time deviation of ≤10μs. Different channels can be grouped and configured with different sampling rates—for example, the first 4 channels can be set to 1000 SPS high-speed mode to monitor high-speed reaction process parameters, while the last 4 channels can be set to 10 SPS low-speed mode to monitor stable level parameters. This balances dynamic response and data transmission efficiency, reducing system communication load.

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• Full-Dimensional Diagnosis and Early Warning, Convenient and Efficient Operation & Maintenance: It is equipped with comprehensive online diagnosis functions, enabling real-time monitoring of the operating status of the module's internal core components (A/D converter, logic circuit, communication interface, power module, cold-junction compensation circuit), input channels (sensor disconnection, short circuit, signal over-range, signal drift), and power supply status (logic power failure, sensor power failure). Diagnostic information includes fault type, faulty channel, fault occurrence time, and fault level (warning/fault/critical fault), which can be viewed remotely and traced historically via Control Builder M software, or displayed intuitively on-site through LED indicators on the front of the module (power indicator, operation indicator, channel status indicator, fault indicator). It supports fault early warning: when potential fault signs such as signal drift exceeding the threshold, expired calibration coefficients, or sensor aging are detected, early warning signals are sent in advance to assist operation and maintenance personnel in conducting predictive maintenance and avoiding unplanned downtime.

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• Industrial-Grade Reinforced Design, Excellent Environmental Adaptability: It adopts industrial-grade high-reliability components and an all-metal housing design. The housing has excellent heat dissipation performance and mechanical strength, enabling rapid heat dissipation from the module during operation and ensuring stable operation within the standard temperature range of -20~60℃ and the short-term extended temperature range of -40~70℃. It has passed vibration tests (5~150Hz, 3g acceleration) in accordance with IEC 60068-2-6 and shock tests (15g acceleration, 11ms duration) in accordance with IEC 60068-2-27, adapting to equipment operation vibrations and transportation/installation shocks. The module has an IP20 protection rating and is equipped with a dust-proof panel design, which can effectively prevent dust intrusion in industrial sites and adapt to harsh operating environments such as power generation workshops, chemical plants, and metallurgical plants with heavy dust, high temperatures, and strong vibrations.

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• Redundant Configuration Support, Significantly Improved Availability: It supports two redundant configuration methods: module-level redundancy and channel-level redundancy. For module-level redundancy, two AI890 modules can be configured in master-standby mode; when the master module fails, the controller automatically switches to the standby module to receive data, with a switching time of ≤1ms, ensuring uninterrupted data acquisition. For channel-level redundancy, the same analog signal can be connected to channels of two different modules to realize "dual-acquisition" data comparison; the controller judges data validity based on the deviation threshold, and when one channel fails, the data from the other channel is automatically used. It supports hot-swapping: under the condition that the system is not shut down and the controller continues to operate, the module can be directly inserted or removed for maintenance and replacement. After the module is removed, the controller automatically marks the corresponding channel as "faulty" and executes the preset safety logic; after inserting a new module, configuration synchronization is completed and operation is restored within 5 seconds, significantly shortening maintenance downtime.

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IV. Working Principle

As the analog sensing core of the AC 800M control system, the ABB AI835 3BSE008520R1 module adopts the core workflow of "initialization configuration - signal acquisition - conditioning and filtering - digital conversion - data calculation - data transmission - diagnostic feedback" to realize accurate acquisition and reliable transmission of analog parameters in industrial processes. The specific workflow is as follows:

1. Module Initialization and Configuration Loading: After the module is installed in the AC 800M I/O rack and powered on, it automatically starts the initialization process. First, it performs a hardware self-test, sequentially checking the integrity of the 24-bit A/D converter, logic processing unit, communication interface, power module, cold-junction compensation circuit, and 8 input channels. After passing the self-test, it establishes a communication connection with the controller via the I/O rack bus and receives configuration parameters issued by the controller, including the signal type, range, sampling rate, filter parameters, calibration coefficients, linearization curve, and fault threshold for each channel. After initialization, the module sends a "ready" signal to the controller, the LED operation indicator remains on, and it enters the normal working mode. If the self-test fails or the configuration parameters fail to load correctly, a fault alarm is triggered immediately, fault codes are uploaded via the communication bus, and the corresponding fault indicator is lit.

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3. Analog Signal Acquisition and Conditioning: On-site analog sensors (e.g., pressure sensors outputting 4~20mA signals, thermocouples outputting mV-level signals) convert industrial process physical quantities (pressure, temperature, etc.) into analog electrical signals, which are transmitted to the corresponding input channels of the module. The module performs differentiated conditioning based on the signal type configured for the channel: Voltage/current signals are isolated by a differential input circuit and then sent to a Programmable Gain Amplifier (PGA), where they are amplified to a standard amplitude suitable for the A/D converter according to the configured range. Thermocouple signals first enter the cold-junction compensation circuit; a built-in high-precision temperature sensor collects the module's ambient temperature, and the impact of cold-junction temperature on measurement is corrected via a compensation algorithm before signal amplification. RTD signals are supplied with a stable excitation current by a constant current source; the resistance value is calculated by measuring the voltage across the RTD, and a lead compensation circuit is used to offset the impact of lead resistance. All signals pass through an RC hardware filter circuit to initially filter high-frequency noise and pulse interference, ensuring the stability of signals entering the conversion stage.

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5. Digital Conversion and Data Calculation: The conditioned standard analog signals are sent to the 24-bit high-precision A/D converter and converted into digital signals. The logic processing unit performs calculation processing on the digital signals according to the configuration parameters: Voltage/current signals are converted into corresponding physical quantities via calibration coefficients (e.g., 4~20mA corresponding to 0~10MPa pressure); thermocouple signals are converted into temperature values by combining cold-junction compensation data and a thermocouple Degree table; RTD signals are converted into temperature values via a resistance-temperature curve (e.g., the ITS-90 Degree table for Pt100). At the same time, an adaptive digital filtering algorithm is executed to adjust filter parameters according to the sampling rate and noise characteristics, filtering out random noise; system errors are corrected via multi-point linear calibration coefficients; for non-linear sensor signals, the configured linearization curve is called for correction to ensure data accuracy. After calculation, the data is checked by a consistency verification unit to eliminate abnormal values.