DPDT Relay Board

This function board is used to control larger loads while isolating them from the web gateway itself. Uses from this board include controlling a motor or lamp and interfacing with garage door wall mounted push button.

The relay used on this board is double-pull double-throw mechanical relay. The relay coil is activated by a transistor connected to a digital output pin on an I/O channel. The relay’s switch contacts are accessible via screw terminals.

Screw terminal blocks are isolated from each other, meaning two devices with different power sources may be switched at the same time. The screw terminal labels are found on the underside of the relay board.

C: Common
NC: Normally Closed
NO: Normally Open

When the relay is in the OFF state, there will be a connection between C and NC only. When the relay is in the ON state, there will be a connection between C and NO only.

This board also has a “pass-through” I/O channel connector. The pass-through connector provides access to the signal lines for other function boards. For example, a temperature probe can be plugged into the back of the relay board and both can work independently. Note that there is only one digital output line on any give I/O channel. Anything connected to the digital output line of the pass-through connector will switch along with the relay board.