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CHAPTER 3: Configuring the Hardware DIP Switches
3.1.5 S
WITCHES
S1-6
AND
S1-7: S
YSTEM
C
LOCK
M
ODE
Use Switches S1-6 and S1-7 to configure the IDSL Line Driver for internal,
external, or receive recover clock mode.
Table 3-6. System clock mode.
S1-6
S1-7
Clock Mode
Description
On
On
Internal
System clock generated internally
Off
On
External (DTE)
System clock derived from terminal
interface
On
Off
Receive Recover
System clock derived from the
received line signal
Off
Off
Hardware Reset
IMPORTANT!
A pair of IDSL line drivers communicate synchronously across the
twisted-pair line connection. Therefore, you must set these switches
regardless of whether your application is async or sync. For X.21 or
async applications, configure one unit for internal clock mode and the
other unit for receive recover clock mode.
3.1.6 S
WITCH
S1-8: R
ESPONSE TO
RDL R
EQUEST
Use Switch S1-8 to allow the IDSL Line Driver to enter the Remote Digital
Loopback diagnostic test when requested to do so by the far end Line Driver. For
example, when switch S1-8 is set to “ON,” it will enter RDL mode (see
Section 5.3.2
) when requested to do so by the remote Line Driver.
Table 3-7. Remote digital loopback test.
S1-8
Setting
On
Response to RDL Request Enabled
Off
Response to RDL Request Disabled
