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Configuring the DTE Clock Rate

By default, the serial interface has a clock rate of 16.384 MHz. For EIA-530 and V.35 interfaces with DTE clocking mode configured, you can configure the clock rate. For more information about DTE clocking mode, see Configuring the Serial Clocking Mode.

To configure the clock rate, include the clock-rate statement:




clock-rate rate;

You can include the clock-rate statement at the following hierarchy levels:

[edit interfaces se-pim/0/port serial-options]
[edit interfaces se-fpc/pic/port serial-options]

You can configure the following interface speeds:

2.048 MHz
2.341 MHz
2.731 MHz
3.277 MHz
4.096 MHz
5.461 MHz
8.192 MHz
16.384 MHz

Although the serial interface is intended for use at the default rate of 16.384 MHz, you might need to use a slower rate if any of the following conditions prevail:

The interconnecting cable is too long for effective operation.
The interconnecting cable is exposed to an extraneous noise source that might cause an unwanted voltage in excess of +1 volt measured differentially between the signal conductor and circuit common at the load end of the cable, with a 50-ohm resistor substituted for the generator.
You need to minimize interference with other signals.
You need to invert signals.

For detailed information about the relationship between signaling rate and interface cable distance, see the following standards:

EIA-422-A, Electrical Characteristics of Balanced Voltage Digital Interface Circuits
EIA-423-A, Electrical Characteristics of Unbalanced Voltage Digital Interface Circuits

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