Multitech MultiModem II BA-Series, User Manual

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Chapter 5 - Command Mode
Unix UUCP Spoofing $SP
The modem can be configured in a Unix environment that employs ACK flow control as a means of
monitoring data integrity. The modem can do “UUCP spoofing”, where the modem is able to generate
ACKs at the DTE interface. Data is transmitted more time efficiently because the delay of waiting for
data to be received, then for an ACK to be returned at the remote end, is eliminated. The $SP1
command enables UUCP spoofing and the default command $SP0 disables UUCP spoofing.
Async/Sync Mode Switching &M
This command can be used to set the on-line mode to either synchronous or asynchronous. AT&M0
will set the modem to Asynchronous mode, and all communications will be Asynchronous, in both
On-line and Command modes. AT&M1 causes the modem to communicate asynchronously when in
Command mode and switch to synchronous mode while on-line. The modem defaults to &M0
(asynchronous communications) on reset or power-up.
Synchronous Transmit Clock Select &X
The &X command selects the Synchronous Transmit Clock Source in conjunction with DIP-Switch
#11. DIP-Switch #11 in the UP position enables External clocking. DIP-Switch #11 in the DOWN
position enables Internal clocking (default position). External clocking is when the DTE provides
transmit clocking to the modem on pin 24 of the RS-232C interface.
&X0 is the default setting, which allows DIP-Switch #11 to control Internal/External Clocking (default
Internal). Internal clocking is when the modem provides transmit clock to the DTE on pin 15 of the
RS-232C/V.24 interface. The &X1 command overrides DIP-Switch #11 and selects External clocking.
If DIP-Switch #11 is UP (External clocking), you can not override Internal clocking. &X2 enables
Slave Clocking. The &X2 Command causes the modem to generate the transmit clock timing (pin 15)
from the receive clock (pin 17) from the DTE (therefore 15 and 17 are the same). In this mode (Slave
Clocking), all timing is controlled by the receive clock.