Loopback Adapters and Crossover Cables for T1 and DDS Circuits
Loopback Adapters and Crossover Cables for T1 and DDS Circuits
Loopback adapters and crossover cables are useful tools for troubleshooting both DDS & T1 circuits. This document shows the necessary pinout for building them.
Where is Pin 1?
Figure 1 shows a how to orient a standard RJ-45 to RJ-45 silver satin cable to determine pin 1. There are eight pins total in a RJ-45 connector.
Figure 1
T1 Loopback Adapter
Figure 2 shows the pinout for building a T1 loopback adapter. This pinout is the same for both a RJ-45 plug and RJ-45 jack.
Figure 2
T1 Crossover Cable
Figure 3 shows the pinout for building a T1 crossover cable. This cable can be used to connect two T1 CSU/DSU (i.e.,TSU) products in a back-to-back configuration.
Figure 3
DDS Loopback Adapter
Figure 4 shows the pinout for building a DDS loopback adapter. This pinout is the same for both a RJ-45 plug and RJ-45 jack.
Figure 4
DDS Crossover Cable
Figure 5 shows the pinout for building a DDS crossover cable. This cable can be used to connect two DDS CSU/DSU (i.e., DSU) products in a back-to-back configuration.