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Clock source.
1. FIB CLK – Fiber clock. With strap, clock is extracted from incoming signal
on fiber.
2. EXT CLK – External clock. With strap clock is extracted from signal on
electrical interface.
3. Internal clock. No strap on FIB CLK and no strap on EXT CLK. Clock is
generated internally in 21.16xx.
4. SYNC - If the data received from the fiber needs to be synchronized in phase
with the data from the electrical interface, position a jumper at the SYNC
(lower) position of S14 and place the jumper S13 according to the brightest
LED, H13 – H14.
Internal clock – “Master mode”
When internal clock is selected, no straps on EXT CLK and FIB CLK, the clock used
is generated by an internal clock. This is used when two 21-16xx, (or other product
with same fiber protocol), are directly connected to each other. Only one 21-16xx
shall have this configuration.
If both local 21-16xx and remote 21-16xx has Internal Clock selected the link works
in Asynchronous mode. Only X.21 and RS530 interfaces support Asynchronous
mode. S11 shall be set to position 2048kbps. Maximum data rate is 256kbps in
asynchronous mode.
