VMIC VMIVME-3230 Thermocouple Input Board

Module Feature

VMIC VMIVME-3230 is a single-slot 6U VMEbus intelligent low-level analog input board dedicated for thermocouple measurement. It integrates 8 galvanically isolated differential input channels, supporting multiple thermocouple types including J, K, T, E, R, S, B, N and W-Re. Onboard 16-bit microcontroller executes cold junction compensation and thermocouple curve linearization, converting microvolt-level thermoelectric signals directly into engineering temperature units. ADC adopts 12-bit plus sign architecture; common-mode rejection reaches 120 dB at 60 Hz, 1000 V isolation between field side and VME backplane. Each input channel carries analog filter and normal-mode overvoltage protection circuit. Calibration parameters are saved in non-volatile memory, no manual potentiometer adjustment required. Measurement unit, resolution and data format can be selected by software. Dual-port register design reduces host CPU overhead. Supports A16/A24 VME addressing and 8/16/32 bit data transfer. Thermocouple wiring connects to screw terminal block via front panel P3 connector, also supports remote cold junction sensor layout. Rugged Eurocard construction, widely used for gas/steam turbine temperature monitoring, power plant process acquisition, aerospace thermal test bench and industrial furnace temperature measurement VME chassis.

Working principle

Weak thermocouple millivolt signals enter differential isolation circuit and low-pass filter before feeding to ADC. Onboard micro reads cold junction temperature to compensate reference junction drift, then performs linearization calculation for selected thermocouple type and outputs standard temperature value. Processed temperature data is stored in dual-port RAM for VME master reading. Nonvolatile memory retains factory calibration coefficients. VME slave interface handles address decoding and data handshake; register set allows host to configure thermocouple type, sampling rate and engineering unit mode. Overvoltage protection circuit clamps transient surge to protect ADC and isolation components.

Onboard components

8 channel differential signal conditioning array,12-bit+sign ADC chip,16-bit onboard microcontroller, cold junction temperature sensor, nonvolatile calibration memory, linearization calculation firmware, high common-mode isolation circuit, input filter and surge protection network, VME address decode logic, dual-port data register, front panel P3 screw terminal connector, status LED array.

LED indicators

Front panel LED indicators for board +5 V power, analog input fault and conversion active status.

Hardware self-diagnosis

Visual inspection of PCB, front ejectors and solder joints; board ID register readback verification; calibration parameter integrity check; per-channel ADC self-test; cold junction sensor validation; thermocouple type switching test; VME 8/16/32 bit read/write communication test.

Programming software

VMIC VME device driver library, universal temperature acquisition and channel configuration utility, compatible with VxWorks, Linux and Windows embedded real-time operating systems.

Electrical & Process Parameters

Model: VMIVME-3230 Device type: 6U VMEbus isolated thermocouple low-level input module Bus standard: VMEbus, A16/A24 addressing, 8/16/32 bit transfer Channel count: 8 isolated differential thermocouple channels ADC resolution: 12 bit plus sign Thermocouple types: J, K, T, E, R, S, B, N, W-Re Isolation rating: 1000 V between field and VME backplane CMRR: 120 dB @60 Hz Control mode: VME slave access, cold junction compensation, built-in linearization, nonvolatile calibration storage Power supply: +5 V from VME backplane Cooling: Convection cooling Protection: Normal mode overvoltage protection, analog input filter, ESD protection Mounting: Standard 6U VME front panel ejector locking Protection class: PCB with optional conformal coating

Mechanical & Structure

Mounting: Standard single-slot 6U VME Eurocard Protection class: PCB with optional conformal coating

Environmental

Operating temperature: 0℃ ~ +60℃ Storage temperature: -40℃ ~ +85℃ Ambient humidity: 5~95% non-condensing Certification: CE compliant Status: VMIC 8 channel isolated VME thermocouple temperature acquisition board

Installation

Follow ESD safety procedure before handling. Fully power off VME chassis. Insert VMIVME-3230 into vacant 6U VME slot and lock front panel ejector latches. Set VME base address via onboard jumpers. Wire thermocouple probes to front P3 screw terminal block, select local or remote cold junction mode. Power on chassis, load VMIC VME driver, configure thermocouple type for each channel and run channel self-test before commissioning.

Interface

VME J1/J2 backplane connector, front panel P3 screw terminal block for thermocouple signals, fault status signal pins.

Diagnostic

Board undetected: poor VME backplane contact, damaged edge connector, incorrect address jumper setting. Temperature reading drift: cold junction sensor fault, thermocouple wiring reversal or loose terminal contact. Channel reading abnormal: broken thermocouple wire, input overvoltage triggered protection, ADC circuit damage. Calibration loss: nonvolatile memory failure.

Product Brief

VMIVME-3230 VMIC single height 6U VME thermocouple input board,eight isolated differential low-level channels with cold junction compensation and thermocouple linearization,for power plant turbine temperature monitoring,industrial furnace and aerospace thermal test VME data acquisition systems.