The driver board allows you to attach up to 8 Triklits via the RJ11 jacks.
The driver board works along with a control board, such as the ethernet or SD-card boards. The driver boards can be stacked, and are attached via a daisy chained ribbon cable.
Each driver board has a jumper to let you set its address from 1 to 8, allowing up to 64 Triklits to be attached, depending on the capabilities of the controller board. Each driver board needs approximately 75ma. The power is received over the ribbon cable from the control board. The jack on the left is number 1.