Cabling the SRP I/O Module

The next step in cabling the system is to connect cables to your SRP I/O module. See Figure 4-3.

Note: The alarm function on the SRP I/O module is currently not implemented.

Cable connections to your SRP I/O module are divided into two sections: external timing ports and console ports. Table 4-2 shows the specifications for each section.

Table 4-2 SRP I/O ports 

Port	Description
External Timing Ports	Two 3-pin wire-wrap posts for US external clock sources; primary (A) and secondary (B) Two BNC connectors for E1 clock sources; primary (A) and secondary (B)
Console Ports	One 10/100Base-T Ethernet management port with an RJ-48C connector One RS-232 port with a DB-9 connector for VT100 management access

External Timing Ports

Two external clock source input ports provide a method of ensuring that the system's clock timing remains synchronized with the network's system clock. The primary clock is labeled A; the secondary, redundant clock is labeled B. Use the connectors appropriate for your area:

• Two 75-ohm E1 2.048-Mbps inputs with BNC connectors
• Two 100-ohm T1 inputs with three pin wire-wrap connectors. Pins are labeled T (Tip), G (Ground), and R (Ring). We recommend using 26-AWG wire minimum.

Note: Use shielded cables to connect the external clock sources to the clock source input ports.

Figure 4-3 SRP I/O module

To connect the clock source input ports:

1. Depending on the connector type, complete one of the following tasks:

• E1: Attach the BNC connector to Clock A's External Timing port.
• T1: Wrap the "Tip" wire on pin marked T of Clock A's External Timing port, the "Ground" wire on G pin, and the "Ring" wire on R pin.

Note: You can use a wire-wrap gun to attach wires to pins.

2. Attach the opposite end of the External Timing cable or wires into your network's clock source A.
3. Repeat steps 1 and 2 for the Clock B connections.

Console Ports

There are two ports located in the Console section (as shown in Figure 4-3) that allow management access.

• The 10/100Base-T Ethernet port accepts an RJ-45 (male) connector. This port provides an out-of-band connection. (We ship an Ethernet cable with the system.)
• The RS-232 port accepts a DB-9 (female) connector. This port allows direct CLI access.

Follow this procedure to connect the Console ports. Refer to Figure 4-3 as needed.

1. Insert the male RJ-45 connector into the 10/100Base-T port until it clicks into place.
2. Attach the opposite end of the cable to your appropriate network device.
3. Insert the female DB-9 connector into the RS-232 port until it is secure.
4. Hand-tighten the DB-9 connector screws.
5. Attach the opposite end of the cable to your terminal (VT100/ANSI).

See Chapter 5, Accessing the ERX System, for more information about management access.