Configuring the Serial Signal Handling
By default, normal signal handling is enabled for all signals. For each signal, the normal option applies to the normal signal handling for that signal, as defined by the following standards:
- TIA/EIA Standard 530
- ITU-T Recommendation V.35
- ITU-T Recommendation X.21
Table 1 shows the serial interface modes that support each signal type.
Table 1: Signal Handling by Serial Interface Type
Signal | Serial Interfaces |
|---|---|
| From-DCE signals | |
Clear to send (CTS) | EIA-530 and V.35 |
Data carrier detect (DCD) | EIA-530 and V.35 |
Data set ready (DSR) | EIA-530 and V.35 |
Indication | X.21 only |
Test mode (TM) | EIA-530 only |
| To-DCE signals | |
Control signal | X.21 only |
Data transfer ready (DTR) | EIA-530 and V.35 |
Request to send (RTS) | EIA-530 and V.35 |
You configure serial interface signal characteristics by including the dce-options or dte-options statement:
You can include these statements at the following hierarchy levels:
- [edit interfaces se-pim/0/port serial-options]
- [edit interfaces se-fpc/pic/port serial-options]
For EIA-530 and V.35 interfaces, configure to-DCE signals by including the dtr and rts statements, specifying the assert, de-assert, or normal option:
For X.21 interfaces, configure to-DCE signals by including the control-signal statement, specifying the assert, de-assert, or normal option:
Assertion is when the positive side of a given signal is at potential high-level output voltage (Voh), while the negative side of the same signal is at potential low-level output voltage (Vol). Deassertion is when the positive side of a given signal is at potential Vol, while the negative side of the same signal is at potential Voh.
For the DTR signal, you can configure normal signal handling using the signal for automatic resynchronization by including the dtr statement, and specifying the auto-synchronize option:
The pulse duration of resynchronization can be from 1 through 1000 milliseconds. The offset interval for resynchronization can be from 1 through 31 seconds.
For EIA-530 and V.35 interfaces, configure from-DCE signals by including the cts, dcd, and dsr statements, specifying the ignore, normal, or require option:
For X.21 interfaces, configure from-DCE signals by including the indication statement, specifying the ignore, normal, or require option:
For EIA-530 interfaces only, you can configure from-DCE test-mode (TM) signaling by including the tm statement, specifying the ignore, normal, or require option:
To specify that the from-DCE signal must be asserted, include the require option in the configuration. To specify that the from-DCE signal must be ignored, include the ignore option in the configuration.
 | Note: For V.35 and X.21 interfaces, you cannot include the tm statement in the configuration. For X.21 interfaces, you cannot include the cts, dcd, dsr, dtr, and rts statements in the configuration. For EIA-530 and V.35 interfaces, you cannot include the control-signal and indication statements in the configuration. For a complete list of serial options statements that are not supported by each serial interface mode, see Configuring the Serial Line Protocol. |
To return to the default normal signal handling, delete the require, ignore, assert, de-assert, or auto-synchronize statement from the configuration, as shown in the following example:
To explicitly configure normal signal handling, include the control-signal statement with the normal option:
You can configure the serial interface to ignore all control leads by including the ignore-all statement:
You can include the ignore-all statement in the configuration only if you do not explicitly enable other signal handling options at the [edit interfaces se-pim/0/port serial-options dce-options] or [edit interfaces se-fpc/pic/port serial-options dte-options] hierarchy levels.
You can include the control-signal, cts, dcd, dsr, dtr, indication, rts, and tm statements at the following hierarchy levels:
- [edit interfaces se-pim/0/port serial-options dte-options]
- [edit interfaces se-fpc/pic/port serial-options dte-options]
