Signal path and input configuration
The 6AG1234-4HE30-4XB0: Four analog inputs, each configurable as current (0 to 20 mA) or differential voltage (±10 V, ±5 V, ±2.5 V, -5 to +5 V, -10 to +10 V, -2.5 to +2.5 V). The differential measurement principle means each channel measures the voltage between its two terminals, rejecting common-mode noise up to 12 V — useful when the sensor and the PLC sit on different ground references. Two analog outputs, also configurable for current or voltage. The module draws 2 W typical from the 24 V DC backplane supply.
Diagnostics and fault detection
Diagnostics function is built in — the module reports wire-break, short-circuit, and diagnostic alarms. The alarm output is parameterizable, so you can set which faults trigger a CPU interrupt and which are logged only. For maintenance-spares planning, the module also reports its own status and flags when an input channel is in alarm state.