THDIO-G Modules Outputs

The outputs are optically coupled. The optical coupler (also called an opto- coupler or opto- isolator) provides the transference of the input state while providing complete electrical isolation. Electrical isolation is of paramount importance in applications such as greenhouse control.

The output does not supply any current. In this regard, it may be considered as a normally open, dry contact, switch.

The following diagram gives a simplified schematic.

As seen from the above circuit, the output transistor switches an external signal. The plug is not polarized.

The output transistor is rated at 250 mA (milli-Amperes), 36 Volts DC, and 300 mW (milli-Watts). This rating is for a continuous signal. The output can withstand surge currents of up to 750 mA.

Often, the output is used to trigger high-power loads, such as fans, pumps, or heaters. In this case, the output should be used to switch a power relay. The following schematic shows the use of a secondary high-power relay. Notice that you must drive the relay using an external power source. This schematic shows a DC relay. If the load were an AC relay, then the plug would not be polarized. In either case, the module output can switch the current on and off.

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