Communication 8903-AI-00

Product Introduction

• This device is rack-mounted industrial isolated analog input communication module designed for centralized collection of on-site industrial analog process signals and protocol conversion transmission to upper-level DCS, PLC or SCADA host system.
• The module converts standard field 4–20mA / 0–5VDC analog process signals into digital communication frame data, completes galvanic isolation between field loop side and internal communication bus side to block surge interference from field long-distance wiring.
• All collected real-time analog measurement values, channel fault status and module operating parameters are packaged into standardized industrial bus protocol and uploaded via dedicated backplane communication bus to system main controller.
• The product complies with IEC61131-2 industrial automation and IEC61000 series EMC standards, designed for continuous 24-hour uninterrupted fixed installation inside industrial control cabinet for process industry analog signal centralized acquisition.

3. Model Series Information

• Fixed Core Model Code: 8903-AI-00
• Parent Product Series: 8903 Universal Rack-based I/O & Communication Module Series
• Corresponding Derivative Series Models:
  • 8903-AO-00: Isolated Analog Output Communication Module variant
  • 8903-DI-00: Digital Input Communication expansion module
  • 8903-DO-00: Digital Output Communication expansion module
• Standard PCB Hardware Revision: Rev.A ~ Rev.D, all revision versions retain consistent mounting dimension, pin definition and full electrical parameter specifications.

4. Technical Specifications

4.1 Power Supply Specification

• Internal Backplane Rated Operating Supply Voltage: 24VDC ±10% supplied from system rack backplane bus
• Module Rated Total Power Consumption: 3.8W maximum under full-channel loaded working status
• Internal isolated auxiliary loop excitation power: Built-in isolated 24VDC loop power supply for field two-wire transmitter, single channel maximum supply output current 32mA per input channel.

4.2 Analog Input Channel Specification

• Total Isolated Analog Input Quantity: 8 galvanically isolated single-ended analog input channels
• Supported standard input signal types:
  1. 4~20mA DC current signal (industry standard two-wire transmitter signal)
  2. 0~5VDC / 1~5VDC voltage analog signal
• Each channel independent isolation withstand voltage: 2500VAC dielectric isolation between field side and internal module logic circuit

4.3 Communication Bus Specification

• Internal rack backplane communication interface: Proprietary high-speed parallel backplane bus dedicated to 8903 series rack system, fixed bus communication rate 2Mbps
• External optional auxiliary communication port: Terminal-side RS485 physical interface, factory default Modbus RTU protocol with configurable baud rate from 2400bps up to 19200bps
• Module station address range: Hardware DIP switch configurable station address 1~99 without software modification requirement.

4.4 Environmental & Physical Dimension Specification

• Certified Operating Ambient Temperature Range: 0℃ ~ +60℃
• Storage & transportation temperature range: -40℃ ~ +85℃
• Valid operating relative humidity scope: 5%~95%RH non-condensing environment only
• Overall outer dimension: 132mm(H) × 85mm(W) × 28mm(D)
• Single unit net weight: 0.32kg
• Protection grade of module main body: IP20; exposed wiring terminal area protection grade: IP00.

5. Function Features

1. Independent channel hardware open-circuit and short-circuit automatic detection function; each abnormal channel generates fault flag and transmits fault message via communication bus to upper controller instantly.
2. Built-in digital average filtering algorithm with user programmable filter sampling depth to eliminate industrial field power frequency interference and transient signal burr noise.
3. Nonvolatile onboard EEPROM storage for channel range configuration data, calibrated coefficient and module communication address; all configuration data permanently reserved after complete power failure without parameter loss.
4. Front panel multi-color LED status indicator group: Green LED for normal power supply and communication running, Red LED for channel hardware fault or communication breakdown, Amber LED for single-channel signal out-of-range warning.
5. Onboard DIP switch group realizes rapid selection of input signal type (current/voltage) without upper computer configuration software operation.
6. Real-time channel raw data, engineering scaled value and diagnostic information cyclic uploading via backplane communication bus following fixed system communication scheduling cycle.
7. Supports field engineering unit scaling programming; users set upper/lower engineering range for every individual channel to convert raw electrical value directly into actual physical process value.
8. Module hot-swap compatible with matched standard 8903 series installation rack; single module plug replacement does not interrupt normal running status of remaining modules on the same rack.

6. Performance Parameters

• Full scale basic measurement accuracy: ±0.1%FS under standard 25℃ rated calibration environment
• Single channel ADC conversion cycle: Fixed 2.2ms per independent channel sampling conversion
• Calculated rated MTBF value: ≥350000 continuous working hours within specified operating temperature range
• Full range temperature drift coefficient: ≤8ppm/℃ across complete 0℃~60℃ working temperature span
• Analog input channel common-mode noise rejection ratio: ≥130dB at industrial standard 50Hz power frequency
• Communication bus data transmission error rate: Zero verified bit error under standard rated EMC test environment.

7. Material Composition

1. Outer module plastic frame and front panel housing: UL94-V0 flame retardant black modified ABS engineering plastic with anti-ultraviolet and low temperature anti-brittle formula.
2. Main control PCB substrate: High-Tg FR-4 industrial glass fiber printed circuit board; entire PCB surface coated with acrylic three-proof conformal coating for moisture, sulfurization and mold prevention.
3. Core signal isolation components: AEC-Q102 certified optocoupler chips for per-channel galvanic isolation, industrial wide-temperature Sigma-Delta multi-channel ADC converter.
4. Passive electronic components: Precision metal film fixed resistors, high temperature solid tantalum capacitors, high frequency multilayer ceramic decoupling capacitors rated -40℃~+125℃ working temperature.
5. External wiring terminal base: Glass fiber reinforced PA66 nylon terminal blocks equipped with silver-plated copper alloy spring conductive terminals; terminal function identification marked by permanent laser etching.
6. Internal storage component: Industrial grade serial EEPROM nonvolatile memory chip for configuration parameter storage.

8. Structural Characteristics

• Three-layer layered compact internal layout: Front panel indicator & setting switch layer, middle analog signal conditioning & digital control PCB layer, rear field signal wiring terminal layer.
• Front panel centralized layout: Three-color LED indicator bank, signal type selection DIP switch set, module station address setting DIP switch array.
• Rear side fixed partitioned terminal layout: 8-channel analog input terminal area, RS485 auxiliary communication terminal area; plastic isolation ribs separate different functional terminal regions to prevent accidental short circuit.
• Standard plug-in card structure matching dedicated 8903 series system rack card slot; plastic positioning buckle on card edge completes mechanical locking after full insertion into rack slot to avoid loose vibration during long term operation.
• Independent ground partitioning layout on PCB: Analog signal ground and digital control ground adopt separated wiring layout to suppress crosstalk interference between analog acquisition loop and digital communication circuit.
• Passive natural convection heat dissipation air gap reserved between PCB and outer plastic casing for continuous high-load operating heat dissipation.

9. Working Principle

1. Field Signal Input Stage: On-site industrial two-wire transmitters or voltage sensors output 4–20mA / 0–5VDC analog signal into corresponding isolated input channel terminals; signal passes through overvoltage protection circuit and precision impedance matching conditioning circuit before sending to isolated ADC chip.
2. Analog-Digital Conversion Stage: Per-channel isolated Sigma-Delta ADC converts continuous analog physical signal into discrete digital sampling value; built-in digital filter processes sampled data to remove abnormal transient noise per pre-set filter parameters.
3. Data Scaling & Logic Processing Stage: Core industrial MCU reads filtered digital data, calls pre-stored channel scaling coefficient stored in EEPROM to convert raw digital data into actual engineering physical value; MCU judges whether measured value exceeds pre-set range or channel has open/short fault state.
4. Communication Data Packaging Stage: MCU packs real-time channel measured data, single-channel fault codes and module operating status into standard communication data frame complying with backplane bus protocol.
5. Data Upload Transmission Stage: Packaged data frame is transmitted via rack backplane high-speed communication bus to system main controller; when external RS485 Modbus function is activated, same data is synchronously output to external fieldbus terminal via auxiliary RS485 port.
6. Status Indication Stage: MCU drives corresponding front panel LED indicators to display real-time running, fault or over-range state according to internal logic judgment result.

10. Advantage Highlights

1. Per-channel independent 2500VAC galvanic isolation design completely isolates high surge voltage induced from field long-distance cables, eliminating cross-channel interference and module breakdown risk caused by field abnormal overvoltage intrusion.
2. Hot pluggable rack installation design allows on-site module maintenance and replacement without shutting down entire rack system power supply, shortening equipment downtime for industrial continuous production sites.
3. Onboard nonvolatile parameter storage retains all configuration information permanently; equipment resumes full functional status automatically after power recovery without repeated parameter configuration work.
4. Multi-layer hardware overvoltage, overcurrent and short-circuit protection circuit is integrated inside every input channel to avoid component burnout caused by field wiring misconnection.
5. Dual communication design combining internal backplane bus and external RS485 Modbus realizes flexible system topology selection to match centralized rack installation or distributed field cabinet installation scenarios.
6. Compact plug-in structure reduces cabinet internal occupied space and wiring workload compared with split-type standalone signal collector plus external communication converter solution.
7. Full compliance with international industrial EMC and safety certification standards to satisfy global process factory indoor cabinet installation specifications.

11. Applicable Industries

• Petrochemical Industry: Refinery production workshop, chemical raw material storage tank area temperature/pressure transmitter signal centralized collection and communication transmission.
• Power Generation Industry: Thermal power plant auxiliary water treatment system, boiler auxiliary instrument analog signal remote data uploading.
• Water & Wastewater Treatment Industry: Sewage treatment plant PH, dissolved oxygen, liquid level transmitter signal acquisition for SCADA system docking.
• Pharmaceutical Fine Chemical Industry: Pharmaceutical synthesis workshop raw material pipeline pressure and flow field instrument signal centralized data transmission.
• Metallurgy Industry: Smelting furnace auxiliary cooling system pressure, temperature analog signal remote communication collection.
• Food & Beverage Processing Industry: Automated production line tank level, pipeline flow instrument signal DCS system data upload.
• Natural Gas Distribution Industry: Gas station pipeline pressure and flow transmitter data acquisition for remote monitoring platform connection.

12. Installation Requirements

1. Cabinet Environment Requirement: Install module inside closed industrial control cabinet; cabinet internal ambient temperature must remain within 0℃~+60℃, prohibit installation near heat-generating components such as power transformers and braking resistors.
2. Mechanical Mounting Specification: Insert module along dedicated 8903 series rack card slot guide rail, push fully into slot then lock edge plastic buckle to complete fixed positioning; maintain minimum 15mm upper and lower gap between adjacent modules for heat dissipation airflow circulation.
3. Field Signal Wiring Standard: All analog input field cable uses shielded twisted pair wire; cable shielding layer executes single-point grounding only at cabinet terminal side, field instrument side shielding end remains suspended open circuit.
4. Wire Cross-section Specification: Field analog signal wiring adopts copper conductor with cross-section ≥0.5mm²; RS485 communication bus wiring uses dedicated twisted pair communication cable with cross-section ≥0.75mm².
5. Communication Bus Wiring Rule: External RS485 Modbus bus applies daisy-chain wiring topology; install 120Ω terminal matching resistor at two extreme endpoints of total bus trunk to eliminate signal reflection distortion.
6. Hazardous Area Installation Rule: For Zone2 hazardous classified cabinet installation, all external field instrument wiring must pass certified explosion-proof junction box before accessing module input terminals; direct installation inside Zone0/Zone1 hazardous area is prohibited.

13. Use Precautions

1. Pre-power-on Inspection Rule: Confirm backplane rack 24VDC power supply matches rated specification before module power-on; forbid connecting higher voltage directly to backplane socket to prevent internal circuit permanent damage.
2. Parameter Setting Regulation: Complete DIP switch signal type and station address configuration under full power-off state; parameter modification during powered running will not take effect until module power cycle restart.
3. Calibration Operation Condition: Complete full-channel accuracy calibration under stable ambient temperature 23℃±2℃; calibration execution under ultra-high/low temperature environment is forbidden to guarantee measurement precision.
4. Maintenance Operation Specification: Cut off corresponding rack backplane power supply before module disassembly maintenance inside hazardous classified area; live plug-in and unplug of field signal terminals during powered running is prohibited.
5. Spare Module Storage Standard: Uninstalled spare modules are stored in constant temperature dry warehouse with ambient humidity below 95% non-condensing; long-term storage in high humidity, corrosive gas environment is prohibited.
6. Firmware Upgrade Restriction: Internal module firmware update is only available via manufacturer official dedicated configuration software; burning unknown third-party modified firmware is forbidden to avoid abnormal communication and channel function failure.
7. Daily Cleaning Specification: Only dry anti-static lint-free cloth is allowed to wipe front panel and terminal surface dust; direct contact of PCB and internal terminals with liquid cleaning solvent is permanently prohibited.
8. Overload Usage Ban: Forbid external field two-wire transmitter drawing load current exceeding 32mA per single channel; continuous over-current load causes internal channel excitation power circuit permanent damage.