The PTO2008-A1 protects the 24 V inside the cabinet with a fuse F1 with a rating of 500 mA.
The call stations are connected to 'X5' with single wires or to 'RJ1' with copper Ethernet cable (CAT5). The signals 'RS485', 'Audio In', 'Audio Out' and the fused '24V' are routed to 'X5' and 'RJ1'.
A previous PTO2008-A1 is connected via 'RJ2', and the next PTO2008-A1 is connected via 'RJ3'. The signals 'RS485', 'Audio In', 'Audio Out' and '24V' are routed to 'RJ2' and 'RJ3'.