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CHAPTER 3: Configuration
LK3: (Receive Pair) Pin 2-to-Ground Connection
This setting determines whether or not pin 2 of the receive pair is sent to
earth ground. This connection should
not
be made in most cases.
LK3
Setting
Strap On
Pin 2-to-GND Connection Made
Strap Off
Pin 2-to-GND Connection Broken
LK4: Clock Synchronization (EIA-530 versus X.21)
This setting determines whether clocks are common or separate. Separate
(non-synchronized) clocks are used for the EIA-530 terminal interface.
Common (synchronized) clocks are used for the X.21 terminal interface. If
clocks are synchronized, a DB25-to-DB15 adapter cable should be used
between the MicroNTU G.703 Card and the X.21 terminal device (see the
Appendix
for pinning).
LK4
Setting
Strap On
Clocks Synchronized (X.21)
Strap Off
Clocks Not Synchronized (EIA-530)
LK5: DTE Signal Ground-to-Frame Ground (with Resistor)
This setting determines whether or not the DTE signal ground (DB25 pin 7)
is connected to frame ground (pin 1) by way of a 100-ohm resistor. This
connection is recommended in the EIA-530 specification as a current limiter
for ground-fault events.
LK5
Setting
Strap On
SGND-to-FGND Connection Made
(via 100-ohm resistor)
Strap Off
SGND-to-FGND Connection Broken
