Four 2 A outputs in a 30 mm slice
The Siemens 6ES7138-4FB03-0AB0 is a 4-channel digital output module for the ET 200S distributed I/O system. Each of the four transistor outputs is rated for 2 A continuous at 24 V DC, with a permissible range up to 2.4 A per channel. Total module current is capped at 6 A, so the four channels share a common 6 A budget — you cannot run all four at 2 A simultaneously if the ambient temperature exceeds the derating threshold.
The module delivers 5 A total up to 55 °C, but drops to 4 A total at 40 °C and again at 60 °C. This means the full 2 A per channel is only available when the total load stays under 5 A and the cabinet stays below 55 °C. Typical power loss is 3.5 W — that heat has to leave the 30 mm-wide housing, so spacing in the cabinet matters for maintaining the derating curve.
Safety and diagnostics for fault-tolerant lines
Rated SIL 3 per IEC 61508 and Category 4 per EN 954-1, this module can be used in safety-related applications up to the highest performance level within the ET 200S safety architecture. Built-in diagnostics include wire-break detection (resistance window 12 Ω to 1 kΩ), short-circuit protection, and a red group-error LED (SF). The module reports faults over the backplane bus, so the controller knows exactly which channel dropped.
Physical fit and backplane loading
The module occupies a single ET 200S terminal slot at 30 mm wide, 81 mm tall, and 52 mm deep. It draws 28 mA max from the backplane bus and 100 mA typ from the 24 V load supply when idle. Unshielded cable runs up to 200 m are permitted — adequate for most distributed layouts in a plant. The outputs are transistor-sourced (PNP), with a minimum "1" signal of L+ (-2.0 V) and a voltage drop across the sinking switch of max 0.5 V.