3Com MSR 50, MSR 30, MSR 20 manual Marked TX

32CHAPTER 2: SMART INTERFACE CARDS

If the SIC has been properly installed, follow these steps to connect the cable:

Step 1: Check the type of E1 cable and correctly set the DIP switch (the ex-factory setting of E1/CE1/PRI interface impedance is 75-ohm);

Step 2: Connect the DB-15 connector of E1 cable to SIC-1EPRI/SIC-1E1-F;

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

1When the E1 cable is a 75-ohm unbalanced coaxial cable:

■Directly connect the BNC connector of the cable to the remote equipment if there is no need for extension, or

■Connect the BNC connector of the cable to the coaxial connector and the other end of the coaxial connector to the remote network equipment through a 75-ohm E1 trunk cable, if cable extension is needed.

CAUTION: The wire marked TX in the E1 cable should be connected to the peer
c wire marked RX and the wire marked RX should be connected to the peer wire
marked TX.
Figure 23 Extending an E1 75-ohm non-balanced 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 remote device has 120-ohm interface, it is needed to use a 75-ohm-to-120-ohm adapter or use a 120-ohm cable.

2When the E1 cable is a 120-ohm balanced twisted pair cable:

■Directly connect the RJ-45 connector of the cable to the RJ-45 port of the remote equipment, if there is no need to extend the E1 cable, or

■Connect the RJ-45 connector of the cable to the network connector and the other end of the network connector to the network equipment through a 120-ohm E1 trunk cable, if cable extension is needed.