Black Box LR5200A-R2 Manual De Usuario

These modules may have either the UP/DOWN switch type or the ON/OFF slide switch

type.  Each type is illustrated below.

CSU/DSU

LINE

1 2 3 4

Switches

up

down

When connecting two bridge/routers back-to-back with CSU/DSU link modules, a null-modem

cable is required to crossover the pins on the links.  Crossing over the pins allows two

bridge/routers both configured as DTE interfaces to be connected together.

Switch number 1 determines whether the ATL-CSU/DSU link module will generate clocks or

receive clocks.  When switch 1 is down (on), the normal position, the module receives clock

signals from the connected network.  When switch 1 is up (up), the module will generate clocks.

When a pair of  routers are connected back-to-back with CSU/DSU link modules one module

must be set to generate clocks and one module must be set to receive clocks.

On 64 Kbps units only, switch number 3 determines the mode of the ATL-CSU/DSU.  When

switch 3 is down (on), the ATL-CSU/DSU is in DDS (Digital Data Service) mode for normal

connection to the 64 Kbps digital service.  When switch 3 is up (off), the ATL-CSU/DSU is in

LDM (Limited Distance Modem) mode for back-to-back connection with a null-modem cable.

On 56 Kbps units, the position of switch 3 is not a factor for back-to-back connection with a

null-modem cable.  Switch 1 must still be set as noted above.

A DSU/CSU crossover cable would be constructed as follows:

1 --> 7

2 --> 8

7 --> 1

8 --> 2