Proface APL3000B - Node Box PC - Manual (Page 38)

Chapter 2 Specifications
2-15
Serial Mode Select Switches (SW4 to SW10) operate as shown in the circuit diagram below.
TXD
RTS
SW4
SW9
SW10
SW5
SW7
SW6
SW8
TXA
TXB
RXA
RXB
RTS Automatic control
COM2