Perle PERLE P850, User And System Administration Manual, Page: 90 / 106

Servicing Information
84
The LXT411 CSU/DSU link connection is set to operate at 64
Kbps by default. The link may be set to 56 Kbps via the software
menus if required.
When two CSU/DSU link routers are to be connected via a
leased line in a back to back set-up, the unit must be set to 56
Kbps link speed and a null-modem crossover cable used for the
connection.
A DSU/CSU crossover cable would be constructed as follows:
1 --> 7
2 --> 8
7 --> 1
8 --> 2
T1/E1 Module:
P850 routers with a T1/E1 interface module use a standard RJ45
service connector, pinout specification RJ48C.
Figure C-5 Rear View of the T1/E1 Connector
When two T1/E1 routers are to be connected in a back to back
set-up, a null-modem crossover cable used for the connection.
A T1/E1 crossover cable would be constructed as follows:
1 --> 4
2 --> 5
5 --> 2
4 --> 1
Pins 1 and 2 are receive (1 = ring, 2= tip)
Pins 4 and 5 are transmit (4 = ring, 5= tip)
T1/E1