# Serial Interface Options

Hold Time: Enter the number of milliseconds after an interface has transitioned from up to down (or down to up) before the interface is advertised to the system as being down (or up).

Clock Mode: Specifies the clock source.

Internal: Select this option to use the device's internal clock.

Loop: Select this option to use the DCE's or DTE's receive clock. You must select this option for X.21 serial interfaces.

DCE clocking mode: Uses the TXC clock, which is generated by the DCE specifically to be used by the DTE as the transmit clock of the DTE.

Clock Rate: Select a clock rate for the interface from the drop-down list.

DTE Options: Sets DTE options and control leads.

CTS Signal Handling: From-DCE clear to send (CTS) signal handling.

Normal: Normal CTS signal.

Require: The from-DCE CTS signal must be asserted.

Ignore: Ignore the CTS signal.

DCD Signal Handling: From-DCE data carrier detect (DCD) signal handling.

Normal: Normal DCD signal.

Require: The from-DCE DCD signal must be asserted.

Ignore: Ignore the DCD signal.

DSR Signal Handling: From-DCE data set ready (DSR) signal handling.

Normal: Normal DSR signal.

Require: The from-DCE DSR signal must be asserted.

Ignore: Ignore the DSR signal.

DTR Signal Handling: Data transmit ready (DTR) signal handling.

Normal: Normal DTR signal.

Assert: Assert the DTR signal.

DE-Assert: De-assert the DTR signal.

Auto-Synchronize: Normal DTR signal, with automatic resynchronization.

RTS Signal Handling: To-DCE request to send (RTS) signal handling.

Normal: Normal RTS signal.

Assert: Assert the RTS signal.

DE-Assert: De-assert the RTS signal.

TM Signal Handling: From-DCE test mode (TM) signal handling.

Normal: Normal TM signal.

Require: The from-DCE TM signal must be asserted.

Ignore: Ignore the TM signal.

Ignore All Control Leads: Select this option to ignore all control leads.

Transmitting Clock Invert: Shifts the clock phase 180 degrees.

Line Encoding: Sets line encoding to Non-Return-To-Zero or Non-Return-To-Zero-Invertible.

Loopback Mode: Sets the loopback mode to None, DCE Local, Local, or Remote/LIU.