Connect the 18pin J3 connector on the Rugged SOM to the 18pin J2 connector on the SwitchBlox Rugged. Power the SwitchBlox Rugged through J1 header on the SwitchBlox Rugged and this will also mean that the Rugged SOM will be powered. Therefore, there is no need to power the SwitchBlox Rugged when in this configuration as it shares it’s power rail with Rugged SOM.

SwitchBlox Rugged is the top board. Rugged SOM is the bottom board.