BMXDDI1602 Schneider Electric — Digital input module — input not reading (stuck at 0)
At a glance
- Severity
- DEGRADED
- Domain
- PLC
- Reference standard
- IEC 61131-2
- Product / context
- DI 16x24VDC — Modicon M340
What it means
A digital input channel on the PLC remains stuck at 0 (FALSE) despite the field sensor or contact being active. The channel status LED on the module does not light up. The problem may be in the wiring, the sensor, or the module itself.
Probable causes
- Broken cable or loose terminal on the module terminal strip.
- Faulty sensor or missing sensor supply (PNP/NPN without 24V).
- Module channel burned out due to overvoltage or short circuit.
- Incorrect input address in the PLC program (variable mapped to the wrong channel).
Where to start
Using a multimeter, measure the voltage between the input terminal in question and the common (0V/M) directly on the module terminal strip. Do you read 24VDC when the sensor is activated?
Full guided diagnosis in the app
The diagnostic tree for this fault has 7 guided steps with measurements, checks and resolutions. You'll find it in ElectraIQ, one of the four IndexOS apps: free, works offline.
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