ZyXEL U-1496S Plus User Guide - Page 63

The U-1496, U-1496E, U-1496P, and U-1496R stand alone, portable, and rack mountable

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terminal. Be sure that the remote modem and system are also set to synchronous. Synchronous operation applies to all the non-FSK modes that the modem is supplied with. The U-1496, U-1496E, U-1496P, and U-1496R stand alone, portable, and rack mountable models support synchronous mode operation, but the U-1496B has a built-in PC asynchronous serial port and can only be used in asynchronous mode. Before you start to send and receive data synchronously, some initial settings should be made. CLOCK OPTIONS Synchronous data must be transmitted and received with a common timing clock. This timing clock is used to transmit data from the DTE to modem and the modem modulates the data according to this clock. The receiving modem recovers the clock and data from the carrier and sends the data to the receiving DTE along with the clock. Generally, there are three types of transmitting synchronous clock sources you can choose from. Internal clock is the one that suits most applications and is the default. Here, the clock signal is generated by the sending modem. Slave clock is used when in remote digital loopback mode. External clock is a signal which is generated by the sendeing DTE. + INTERNAL AT&X0 Modem provides the clock and sends it to DTE. Adaptive rate can be used. (Default.) EXTERNAL AT&X1 DTE provides the clock and sends it to modem. Must use auto- retrain, cannot use adaptive rate. SLAVE AT&X2 Modem recovered receiver clock is used as the transmit clock. RTS OPTIONS There are two RTS options. The choice depends on application and host/terminal requirements. This setting is ignored in asynchronous mode where RTS is used as a hardware flow control signal. + RTS IGNORED AT&R1 Modem ignores RTS, assumes RTS always ON. (Default). CTS TRACKS AT&R0 Delay before CTS responds to RTS's change. The delay is set in S26 register. Half-Duplex Operation For a half-duplex modem, the carrier only exists in one direction at any specific time. The carrier, local CTS signal, and remote CD signal will follow the RTS signal in a certain manner. Some communication software written for half-duplex modems rely on the RTS, CTS, and CD signals. For a full-duplex modem, carriers are always present in both directions. In order for it to simulate a half-duplex modem, V.13 protocol is provided to have the local CD signal follow the remote modem's RTS signal. Set S44.5=1 to enable V.13. MODE OPTIONS For synchronous data communication, there are two options you can choose to define how the modem will operate in the command state.

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terminal. Be sure that the remote modem and system are also set to synchronous. Synchronous
operation applies to all the non-FSK modes that the modem is supplied with.
The U-1496, U-1496E, U-1496P, and U-1496R stand alone, portable, and rack mountable
models support synchronous mode operation, but the U-1496B has a built-in PC asynchronous
serial port and can only be used in asynchronous mode.
Before you start to send and receive data synchronously, some initial settings should be made.
CLOCK OPTIONS
Synchronous data must be transmitted and received with a common timing clock. This timing
clock is used to transmit data from the DTE to modem and the modem modulates the data
according to this clock. The receiving modem recovers the clock and data from the carrier and
sends the data to the receiving DTE along with the clock. Generally, there are three types of
transmitting synchronous clock sources you can choose from. Internal clock is the one that suits
most applications and is the default. Here, the clock signal is generated by the sending modem.
Slave clock is used when in remote digital loopback mode. External clock is a signal which is
generated by the sendeing DTE.
+
INTERNAL
AT&X0
Modem provides the clock and sends it to DTE. Adaptive rate
can be used.
(Default.)
EXTERNAL
AT&X1
DTE provides the clock and sends it to modem. Must use auto-
retrain, cannot use adaptive rate.
SLAVE AT&X2
Modem recovered receiver clock is used as the transmit clock.
RTS OPTIONS
There are two RTS options. The choice depends on application and host/terminal requirements.
This setting is ignored in asynchronous mode where RTS is used as a hardware flow control
signal.
+
IGNORED
AT&R1 Modem ignores RTS, assumes RTS always ON. (Default).
CTS TRACKS
RTS
AT&R0 Delay before CTS responds to RTS's change. The delay is set in S26 register.
Half-Duplex Operation
For a half-duplex modem, the carrier only exists in one direction at any specific time.
The
carrier, local CTS signal, and remote CD signal will follow the RTS signal in a certain manner.
Some communication software written for half-duplex modems rely on the RTS, CTS, and CD
signals.
For a full-duplex modem, carriers are always present in both directions.
In order for it to
simulate a half-duplex modem, V.13 protocol is provided to have the local CD signal follow the
remote modem's RTS signal.
Set S44.5=1 to enable V.13.
MODE OPTIONS
For synchronous data communication, there are two options you can choose to define how the
modem will operate in the command state.