The Siemens 6ES7143-4BF50-0AA0 is an ET 200SP module with four digital inputs and four digital outputs on a 45 mm footprint. Each channel is individually monitored—the green status indicators tell you at a glance which sensor or load is live. Short-circuit protection is per channel and electronic, tripping at a typical response threshold of 0.7 A. That keeps a bad photocell from taking down the whole slice. Diagnostic alarms are readable over the backplane, so the PLC knows exactly where the fault is.
The module draws a maximum of 20 mA from the backplane bus, leaving headroom for additional slices. Input thresholds for the low state range from -3 to +5 V, and for the high state from +11 to +30 V. Output is rated at 0.5 A per channel with resistive load switching up to 100 Hz.