Checking Input Signal vs. Displayed Value on Red Lion Panel Meters

Description: Red Lion panel meters: how to verify the input signal against the displayed value when troubleshooting an incorrect process reading.

APPLICABLE PRODUCTS

Red Lion Controls panel meters with analog inputs, including models configured for signals such as 4–20 mA or 0–10 VDC. The specific procedure and available parameters depend on the meter model.

ISSUE / QUESTION / SYMPTOM

The Red Lion panel meter displays a process value that does not appear to match the actual process condition or the expected value from the field transmitter.

Before replacing the meter or transmitter, verify that the electrical input signal reaching the meter corresponds to the value being displayed.

POSSIBLE CAUSES / ANSWER

The discrepancy can be caused by the field device, wiring, input signal, meter scaling, or meter configuration.

Use the following procedure to isolate the source of the problem:

1. Identify the meter input type.
   Verify whether the meter is configured for 4–20 mA, 0–10 VDC, thermocouple, RTD, pulse/frequency, or another supported input type.
2. Determine the expected signal-to-display relationship.
   For example, a pressure transmitter may be scaled as:
   • 4 mA = 0 PSI
   • 20 mA = 100 PSI

With this scaling, 12 mA should correspond to approximately 50 PSI.

1. Measure the actual input signal at the Red Lion meter.
   Using appropriately rated test equipment and the correct measurement method for the circuit, measure the signal directly at the meter input terminals.
2. Compare the measured signal with the displayed value.
   • Incorrect input signal: If the signal reaching the meter is not what is expected, investigate the transmitter, power supply, wiring, terminals, or other devices in the signal path.
   • Correct input signal but incorrect display: If the measured signal is correct but the displayed value is incorrect, verify the meter's input configuration and scaling parameters.
   • Correct signal and correct display but incorrect process value: If the meter accurately represents the input signal but the process measurement is incorrect, investigate the transmitter or the actual process condition.
3. Verify the meter scaling.
   Check the configured input and display values. For a typical 4–20 mA application, verify:
   • Input low value
   • Input high value
   • Display low value
   • Display high value
   • Decimal position
   • Offset or correction settings
   • Any applicable filtering or averaging settings
4. Check the signal at multiple points if necessary.
   If the signal at the transmitter does not match the signal at the Red Lion meter, measure at intermediate points such as junction boxes and terminal blocks. This can help identify loose connections, damaged conductors, incorrect wiring, or other signal-path problems.

Example:

A pressure transmitter is configured for 4–20 mA = 0–100 PSI. The Red Lion meter displays 72 PSI.

The input signal is measured directly at the meter and is found to be 12.0 mA.

Since 12 mA corresponds to approximately 50 PSI with the stated scaling, the input signal is correct, but the displayed value is not. The next step is to verify the Red Lion meter's scaling and configuration rather than replacing the transmitter.

Troubleshooting sequence:

Process → Transmitter → Wiring → Input Signal → Meter Configuration → Display

Verifying the actual input signal before changing the meter configuration helps determine whether the problem is with the field signal or the panel meter and can prevent unnecessary component replacement.

ADDITIONAL INFO

Always follow the installation and operating instructions for the specific Red Lion meter model. Use appropriately rated test equipment and follow applicable electrical safety procedures when testing energized control panels.

For model-specific input ranges, programming parameters, and wiring information, refer to the applicable Red Lion product manual.

If you still need assistance, please contact HMS Technical Support here: HMS Support Portal

© HMS Networks AB 2026