Product Description:

B & R Automation manufactures the 7DO138.70 digital output module for the System 2003 Controllers series. As an output slice for these PLC racks, it translates control signals into DC switching of field devices such as solenoid valves and indicator lamps. It is intended for cabinet-based automation systems that need direct control of multiple loads from a compact PLC assembly.

The module uses an external 24 V supply rail and draws 1.5 W, while its logic section consumes 0.25 W from the internal backplane. Keeping those power paths separate helps reduce crosstalk in mixed I/O stations. All outputs share a rated bus of 24 VDC, and each channel can source up to 0.5 A through a positive-switching FET stage, so inductive loads can be driven without mechanical wear. The circuit is configured as a sourcing type, meaning current flows from the module to the load. Screw-in terminals secure field wiring, and the sensor supply must be provided externally because no onboard auxiliary voltage is generated.

The card provides 8 parallel channels that can be wired in groups for higher current, but the total load must remain below 4.0 A across the common pin. The housing has an IP20 rating for cabinet use, and reverse-polarity protection helps prevent damage if the leads are connected incorrectly. Short-circuit detection shuts off a faulted line, and thermal overload monitoring limits junction temperature before automatically resetting when conditions return to normal. Because the outputs tie directly to the controller power domain, there is no galvanic isolation to the PLC backplane when grounds are mixed. The outputs can also be paralleled for actuators with higher inrush demand, and screw mounting into the System 2003 rail helps keep installation stable under vibration.