Foxboro FBM203 P0914SV 8-Channel Isolated RTD Input Module

Power not connected or wiring error (positive and negative poles reversed).

Power voltage exceeds the allowable range (e.g., 24VDC power fluctuates by more than ±10%).

Power circuit fuse blown or power module failure.

Check power wiring, confirm the positive and negative poles of the 24VDC power supply (red wire to +, black wire to -), and use a multimeter to measure the power voltage.

Replace the power circuit fuse; if ineffective, replace the power module or check the control cabinet power supply system.

FOUNDATION Fieldbus cable disconnected, short-circuited, or poorly connected.

Bus impedance mismatch (terminating resistor not connected or damaged).

Incorrect module address setting or address conflict with other modules.

Communication interface failure on the controller side.

Check bus cable connections, re-plug or replace shielded twisted-pair cables, ensure correct bus topology (tree/bus type), and install a 100Ω terminating resistor at the end.

Use a multimeter to measure bus impedance and confirm normal resistance; check the module address (e.g., Slot number) in the configuration software to match the actual installation location.

Restart the module or controller; if ineffective, replace the controller communication card.

Loose, short-circuited, or open field signal wiring (e.g., 4-20mA signal disconnection).

Incorrect signal type configuration (e.g., mistakenly set to voltage input during configuration while actually connecting current signal).

Hardware failure in the module channel (e.g., damaged internal amplifier or A/D converter).

Signal distortion due to electromagnetic interference (e.g., unshielded cable or proximity to strong electromagnetic sources).

Check terminal block wiring, use a multimeter to measure field signals (e.g., whether 4-20mA signals are within the normal range), and re-tighten the wiring.

Confirm correct setting of channel parameters (signal type, range, filtering time) in the configuration software; for example, set the range for 4-20mA to 0-100%.

Test with a spare module of the same type; if the fault transfers, the original module channel is damaged and needs repair or replacement.

Add a shielding layer to the signal cable and ground it reliably, keeping it away from interference sources like frequency converters and transformers.

Module uncalibrated or calibration expired, causing zero/full-scale drift.

Voltage drop in the input signal loop (e.g., Too long cable length or too thin wire diameter).

Incorrect cold junction compensation setting (if related to temperature signals).

Ambient temperature exceeds the module's operating range (-20℃~+60℃), causing component performance fluctuations.

Use calibration equipment (e.g., signal generator) to calibrate the module's zero and full scale, and execute the calibration program in the configuration software.

Check the signal loop resistance (4-20mA loop resistance ≤500Ω), and replace with thicker cables or shorten the wiring distance.

If measuring temperature signals, confirm correct setting of cold junction compensation method (e.g., RTD compensation) and check for loose RTD wiring.

Improve the module installation environment by adding cooling fans or thermal insulation to ensure the temperature stays within the allowable range.

Thermocouple/thermal resistance signal disconnection (burnout detection function triggered).

Input signal exceeds the range (e.g., 4-20mA input exceeds 21mA or is lower than 3.6mA).

Abnormality detected by the module's internal fault diagnosis function (e.g., channel overload).

For thermocouple signals, check sensor wiring for disconnection and replace damaged thermocouples or compensation wires.

Measure whether the input signal is within the rated range; if out of range, check if field instruments (e.g., transmitters) are faulty.

View detailed alarm information in the configuration software to confirm the fault type, and restart the module or replace the channel if necessary.

Poor ventilation in the installation environment with insufficient heat dissipation space (distance between modules <50mm).

Excessive temperature in the control cabinet without cooling fans or air conditioners.

Internal component short circuit in the module, causing abnormal power consumption.

Ensure sufficient heat dissipation space around the module, install according to specifications (spacing ≥50mm), and avoid stacked installation.

Check the control cabinet ventilation system, install cooling fans or air conditioners, and maintain internal temperature ≤40℃.

After powering off, touch the module surface; if a certain area is abnormally hot, it may be an internal short circuit, requiring module replacement.