Four inputs that read both AC and DC
The 6ES7131-4CD00-0AB0 is a SIMATIC DP ET 200S electronic module carrying four digital inputs rated for universal voltage from 24 V to 48 V AC/DC (47...63 Hz). It accepts both 24 V AC and 24 V DC supply from the power module. The input thresholds are specified for signal 0 at -6 to +6 V DC or 0 to 5 V AC, and for signal 1 at -15 V DC to -57.6 V DC, 15 V DC to 57.6 V DC, or 15 V AC to 48 V AC. This wide range means the module can handle mixed-voltage field devices without separate input conditioners — a real time-saver when you're wiring a panel with both 24 VDC prox sensors and 48 VAC limit switches on the same slice.
Sizing the slice and the signal chain
At 15 mm wide and 52 mm deep, this module fits the standard ET 200S rail footprint — you can pack up to 16 of these across a 250 mm section. The 81 mm height clears most enclosures without a right-angle adapter. Each input draws a typical 10 mA at signal 1 (4 to 10 mA range), so the total module load at full saturation is about 40 mA from the field supply. The backplane bus draws a max of 10 mA at 3.3 V DC, leaving plenty of headroom on the power module's 500 mA rated capacity. Cable runs are rated up to 1 000 m shielded and 600 m unshielded, which covers most plant-floor distances without a repeater.
Diagnostics and protection that save a service call
The module includes parameterizable diagnostics with a group error SF (red) LED that flags a fault across all four channels. Each channel has its own green status indicator, so you can spot a missing sensor at a glance without plugging in a laptop. Short-circuit protection is built in per module, and reverse polarity protection is automatic for both AC and DC — meaning a swapped wire on a 48 VAC limit switch won't smoke the board. Isolation between the channels and the backplane bus is tested at 2 500 V DC, though there is no channel-to-channel isolation, so keep field wiring on the same potential group. The 2-wire sensor compatibility with a permissible quiescent current of up to 2 mA (0.5 to 2 mA) means it works with most standard proximity sensors; the fixed current limitation for wire-break monitoring uses an 18 kΩ resistor at 24 V or a 39 kΩ resistor at 48 V.