Configuring the Modem
SW2-8 − Carrier Control (high- & low-speed modes)
SW2-8 ON = Constant
OFF = Switched
SW2-8 selects either constant or switched carrier. Constant carrier allows DTEs, such as asynchronous dumb terminals or RTUs, to operate with modems, without the input RTS signal. When constant carrier mode is enabled (SW2-8 set to ON), the modem forces the transmit carrier active and the RTS-CTS delay is minimum (<0.5 ms.).
You can use constant carrier in 4-wire, point-to-point or multi-point applications (from master to slave modems).
In switched-carrier mode (SW2-8 set to OFF), the RTS/CTS delay is 23 ms.
SW 2-9 − RX Termination (high- & low-speed modes)
SW2-9 ON = Disable Rx Termination
OFF = Enable Rx termination
SW2-9 selects whether RX termination is enabled for a modem. If you set this switch OFF, the receiver is terminated with 600 Ω. If you set this switch ON, the receiver is not terminated.
SW 2-10 − Ground Option (high- & low-speed modes)
SW2-10 ON = Modem signal ground is connected to chassis ground OFF = Modem signal ground and chassis ground disconnected
SW2-10 determines the grounding option for the modem. Setting this switch ON connects the modem signal ground to chassis ground. Setting this switch OFF disconnects the modem signal ground from chassis ground.