DIRECT ANSWER
What is the practical starting point?
Troubleshoot a 4–20 mA loop in order: verify supply, polarity and wiring; measure loop current; check total load; confirm range and output configuration; then compare the process input with the transmitter indication.
SELECTION FACTORS
Data to confirm before model selection
Use this list to prepare a traceable quotation request.
- 01Follow site electrical and process safety procedures.
- 02Verify loop supply at the transmitter under load.
- 03Check polarity, terminals, cable continuity and shielding.
- 04Measure current with the correct meter connection.
- 05Confirm scaling, burnout direction and simulation mode.
- 06Compare sensor or process input with transmitter output.
TECHNOLOGY COMPARISON
Compare the decision factors
| Loop result | Likely area | Next check |
|---|---|---|
| 0 mA | Open circuit, polarity or no power | Supply and continuity |
| Below 4 mA | Fault indication or configuration | Diagnostic status and range |
| Fixed current | Simulation, saturation or frozen input | Configuration and process sensor |
| Unstable current | Power, connection, grounding or process noise | Voltage, terminals and shielding |
FAQ
Questions engineers ask first
Last reviewed:
Can a transmitter be tested without the process?
Many transmitters support simulation or a controlled sensor input, but the method is model specific and must follow its documentation.
Why does loop voltage look correct but current stay low?
Check available voltage under load, total loop resistance, configuration, fault status and the process input.
ENGINEERING SUPPORT
Turn process data into a reviewable instrument request.
Share the medium, operating envelope, installation and required output. We will flag missing information before confirming a model.