User`s guide

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Configuration – Network > Interfaces > Serial > Sync
The most common form of serial communications these days is asynchronous. Synchronous
serial communications links are still in use and the Digi routers can support these. HDLC is a
synchronous protocol that is still in use and can be used with Digi routers. This section
describes how to configure the synchronous communications interfaces. To enable
synchronous mode, a protocol such as LAPB must be configured to use a synchronous port
as its lower layer interface. On certain models, an informational message will appear on the
web page which states that jumper settings may need to be changed in order to support
synchronous serial operation.
Note:
The number of synchronous serial ports available will vary depending on the model and any
optional modules fitted.
Description
This text entry box is for a description of the interface, should one be required.
Clock source Internal / External
These two radio buttons select between internal or external clock sources for the interface.
Mode
The radio buttons that appear here select the specific serial protocol to use. Which buttons
appear depend upon the capabilities of the interface. The options available are; V.35,
EIA530, RS232, EIA530A, RS449 and X.21.
Invert RX clock
When checked, this checkbox will cause the router to invert the voltage level of the receive
clock signal.
Invert TX clock
When checked, this checkbox will cause the router to invert the voltage level of the transmit
clock signal.
Encoding NRZ / NRZI
These two radio buttons select between non-return to zero (NRZ) and non-return to zero
(inverted) (NRZI) signal encodings.
Related CLI Commands
Entity
Instance
Parameter
Values
Equivalent Web Parameter
sy 0 descr
Text description of
interface
Description
sy 0 clksrc int,ext Clock source
sy 0 rxclkinv OFF,ON Invert RX clock
sy 0 txclkinv OFF,ON Invert TX clock
sy 0 encode nrz,nrzi Encoding