3Com MSR 30, MSR 20, MSR 50 manual Local Rx wire to the remote Tx wire

MIM-1E1/MIM-2E1/MIM-4E1/MIM-1E1-F/MIM-2E1-F/MIM-4E1-F Modules 87

■By default, all of the DIP switches of MIM-1E1/MIM-2E1/MIM-4E1 and MIM-1E1-F/MIM-2E1-F/MIM-4E1-F modules are factory-configured to ON, that is, the impedance of E1 interface is 75-ohm.

Connecting the Interface Cable

c

CAUTION:

■Read the mark identifying a port before you connect a cable to it, making sure it is the correct port. Wrong connection tends to damage interface modules and even the Router;

■Some protection measures are taken for MIM-1E1/MIM-2E1/MIM-4E1 and MIM-1E1-F/MIM-2E1-F/MIM-4E1-F modules. Still, you are recommended to install a special lightning arrester at the input end of the cable leading to the outdoors in order to protect the line against lightning strikes more efficiently.

Connecting interface cable of MIM-1E1/MIM-2E1 and

MIM-1E1-F/MIM-2E1-F/MIM-4E1-F modules

Step 1: Check the type of E1 cable, and set the DIP switches of MIM-1E1/MIM-2E1 or MIM-1E1-F/MIM-2E1-F module correctly;

Step 2: Plug the DB-15 connector of the E1 cable into the E1/FE1 port on the module;

Step 3: Connect the other end of the E1 cable to the network device;

1When using 75-ohm unbalanced coaxial cable,

■Connect its BNC connector to the device to be connected directly, if cable extension is not needed;

■Connect its BNC connector to a coaxial connector and the other end of the coaxial connector to the device to be connected through a 75-ohm E1 trunk cable, if cable extension is needed;

CAUTION: Connect the local Tx wire in the E1 cable to the remote Rx wire and the
c local Rx wire to the remote Tx wire.
Figure 97 Extending an E1 75-ohm unbalanced coaxial cable
		DB -15			BNC	Network
				BNC
	Router					devices
						such as DDN
			Coaxial connector		75-ohm E1 trunk cable
75-ohm non-balanced coaxial cable

■If the port on the network device to be connected has a 120-ohm port, use a 75-ohm to 120-ohm adapter, or use a 120-ohm cable instead.

2When using a 120-ohm balanced twisted pair cable,