T8431C Analog Input (AI) Module

T8431- ICS Triplex TMR Trusted Analog Input (AI) Module
This is a 4-channel analog input module in the ICS Triplex TRUSTED TMR series, using a Triple Modular Redundancy (TMR) architecture, specifically designed for safety critical industrial control systems.

core positioning
Project Description
Part number T8431
Manufacturer ICS Triplex (now part of Honeywell/Invensys)
TRUSTED TMR (Triple Modular Redundant Fault Tolerant System)
Function type: 4-channel analog input (AI)
Safety level SIL 2/SIL 3 optional
Redundant TMR triple hardware voting, single point failure does not affect output

Key technical parameters
4 input channels (single ended)
Range options -10V~+10V/0~20mA/4~20mA (configurable)
Measurement accuracy 0.01% (after TMR voting)
A/D resolution of 16 bits
Power supply voltage 24 VDC
Power consumption<5W
Communication protocol RS-485 (Modbus RTU)
Baud rate 9600/19200/38400/57600/115200 bps
Maximum communication distance of 1200 meters
Working temperature -40 ℃~+85 ℃
Storage temperature -40 ℃~+125 ℃
Dimensions: 120mm × 80mm × 30mm
Weight approximately 0.5 kg
Protection level IP20 (installed inside the cabinet)
Front panel indicator LED status light (power/communication/fault/channel status)
hot-swapping ✅ Support online replacement without interrupting system operation
TMR redundancy mechanism
Three T8431 modules simultaneously collect the same signal
↓
Hardware level 2-out-of-3 voting
↓
Any module fault → automatic elimination, output not affected
↓
The faulty module can be hot replaced online without shutting down the system
This is the core advantage of the TRUSTED TMR series: no data loss or shutdown due to single module failure, suitable for SIL 2/SIL 3 safety instrumented systems.

Comparison of AI modules in the same series
T8431 4-channel AI standard TMR analog input (this model)
T8432 4-channel AI dual channel analog input (double density)
T8433 4-channel AI isolated analog input (electrically isolated between channels)
T8831 40 channel AI FTA (on-site terminal adapter), high-density
T8832 60 channel AI FTA, higher density
T8833 20 channel AI+DI hybrid FTA
T8844 40 channel AI multifunctional FTA

Typical application scenarios
Temperature, pressure, and flow monitoring of chemical/petrochemical reaction vessels
Power plant turbine vibration, bearing temperature, steam flow rate
Feedback on oil and gas pipeline pressure and valve position
Monitoring of water level, water quality, and flow rate in water treatment
The Safety Instrumented System (SIS) works in conjunction with the T810B processor to achieve ESD emergency shutdown

Supporting system architecture
┌─────────────────────────────────────────┐
T8100/T8300 rack
│ ┌─────┐ ┌─────┐ ┌─────┐ ┌─────┐ │
│ │T8110B│ │T8110B│ │T8110B│ │ T8431│ ← AI │
│ │ CPU │ │ CPU │ │ CPU │ │ ×3 │ │
│ └─────┘ └─────┘ └─────┘ └─────┘ │
│ ┌─────┐ ┌─────┐ ┌─────┐ │
│ │T8403│ │T8451│ │T8480│ ← DI/DO/AO │
│ └─────┘ └─────┘ └─────┘ │
│↑ RS-485 bus connection │
└─────────────────────────────────────────┘

Replacement precautions
Confirm suffix: T8431 is the standard type. If isolation is required, choose T8433, and for double density, choose T8432
Range matching: Before replacement, confirm that the on-site signal type (voltage/current) is consistent with the module range, and the range is configured through the module side jumper or software
TMR pairing: TMR systems require modules of the same type to be used in groups of three, and non TMR modules cannot be mixed
Firmware version: TRUSTED system module firmware is strongly bound to processor version and needs to be matched
Address setting: RS-485 address is set through module DIP switch or configuration software, and needs to be reconfigured after replacement