Patton electronic X.21 Interfaces - Manual (Page 9)

8
SW1-6 and SW1-7 Clock Modes
Use Switches SW1-6 and SW1-7 to configure the 2707 for internal,
external, or receive recover clock mode.
SW1-8: Enable/Disable Loop Tests from DTE
Use Switch SW1-8 to allow Model 2707 to enter loopback tests when the
DTE raises the appropriate loop request pin.
Table 3: SW1-6 and SW1-7 Clock Modes
SW1-6 SW1-7 Clock Mode
ON ON Network (Received Recovered)
ON OFF Internal
OFF ON External
OFF OFF Network (Received Recovered)
Network Clock Transmitter timing is derived using
the received line signal (received
recovered) from the network.
Internal Clock Transmitter timing is derived from
an internal clock source.
External Clock Transmitter timing is derived from
DTE terminal timing.
SW1-8 Setting
Off Response to DTE Loopback Request Enabled
On Response to DTE Loopback Request Disabled