Digital Interface Testers

Communication channels may encounter problems such as congestion due to heavy data traffic or bandwidth waste. To counter such problems, you can use different types of digital interface testers. Digital interface testers are third-party tools used for testing digital signals received by and transmitted from computers and other network devices such as modems, printers, and scanners. These testers are used for both serial and parallel interfaces pertaining to digital signals and data communication.

The digital interface testers identify problems of the data transmission line, capture corrupted data, and detect common problems related to communication channels. Examples of digital interface testers are:

• Breakout boxes

• Fox boxes

• Bit/Block Error Rate Testers (BERTs/BLERTs)

These digital interface–testing tools measure digital signals on peripheral devices such as PCs, printers, and Channel Service Unit/Digital Service Unit (CSU/DSU). They are also responsible for analyzing the data communication line, detecting corrupt data, and preventing corrupted data from reaching the destination node. In addition, these digital interface–testing tools monitor data that is transmitted from Data Terminal Equipment (DTE) through Data Communications Equipment (DCE). While monitoring the data transmission from a DTE through a DCE, these tools identify:

• Corrupted bit patterns

• Improper cabling within a network

• Problematic situations such as traffic congestion during data transmission

For example, if you need to identify a problem in the connection between a CSU/DSU and a router, a breakout box can be deployed between the unit and the router. This helps determine whether the CSU/DSU sets the CTS high before the router transmits the data and sets the DTR high. This test enables you to determine if the router is appropriately transmitting data on the network.

However, the main disadvantage of digital interface–testing tools is that they cannot be used to test media signals from Ethernet, Token Ring, or FDDI. Though these tools test the effectiveness of the communication channel and digital signals, they cannot be used to test protocol-related issues on a communication channel.