The GX6138 consists of three switching groups: A, B and C. Each group has 38 individual relays connected to J6 as shown in the figure below:
GX6138 Architecture
Relays
The GX6138 has 38 Form A (SPST) relays (see the figure below).
A typical GX6138 relay
When the relay is activated, the Change Over (CO) terminal is connected to the Normally Open (NO) terminal. When the relay is deactivated, the CO terminal is disconnected from to the Normally Closed (NO) terminal. After the board is reset, all relays are deactivated. Both sides of the relay are connected to the connector, one side is CHnA and the other is CHnB, where n is 1 to 38 (see the table for J6 Connector's pins ).