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CHAPTER 9: DIP-Switch Settings
Switch #12
Asynchronous/Synchronous Operation -- "Sync"
(Asynchronous/Synchronous Mode/Leased Line/Dial-Up)
The Series II Modem can operate in either Asynchronous mode or
Synchronous mode. In Synchronous mode, start and stop bits are
eliminated. The modem's internal clock circuits on the RS-232C/V.24
pins 15 and 17 are activated. The Series II Modem's Command mode is
not accessible in Synchronous mode. This switch is a means to alternate
and to access either mode. In Synchronous mode, you may want to set
the RTS forcing and CTS forcing DIP-Switches so that both of signals
act normally (not forced on).
Synchronous Operation = Switch #12 UP
Asynchronous Operation = Switch #12 DOWN
Factory Default Setting = DOWN
Switches #13 and #14
Speed Switches
(Synchronous Mode/Leased Line)
DIP-Switches #13 and #14 are used to set the Series II Modem’s data
transmission rate. Switches #13 and #14 are used in combination,
typically in leased-line and call origination applications. Note that the
modem baud rate command ($MB33600) overrides the setting of these
speed selection switches (DIP switches #13 and #14).
28800 bps Operation = Switch #13 UP and Switch #14 UP
19200 bps Operation = Switch #13 DN and Switch #14 UP
14400 bps Operation = Switch #13 UP and Switch #14 DN
9600 bps Operation = Switch #13 DN and Switch #14 DN
Factory Default Setting = Switch #13 UP and Switch #14 UP
Switch #15
Carrier Detect/DSR Forcing -- "DSR"
(Asynchronous/Synchronous Mode/Dial-Up/Leased Line)
Some terminals react in unusual ways to the toggling of the Carrier
Detect (CD - RS-232C/V.24 pin 6) signals. The most common symptom
is that the modem does not respond to commands, or does not echo
characters. In these cases, it is advisable to force these two signals On in
order for the terminal to communicate properly with the modem in