Patton electronic 1184, 1185 and

5.3 DIAGNOSTICS

Model 1184 and 1185 are equipped with V.54 diagnostics that may

be used to to evaluate the condition of the local and remote units, as

well as the twisted pair link between them: local loopback (LAL) and

remote digital loopback (DL).

5.3.1 Local Analog Loopback

The Local Analog Loopback (LAL) test checks the operation of the

local Model 1184 or 1185 and is performed separately on each unit.

Any data sent to the local Model 1184/1185 in this test mode will be

echoed (returned) back to the user device. (See Figure 7, below). For

example, characters typed on the keyboard of a terminal will appear on

the terminal screen.

To perform a Local Analog Loopback test, follow these steps.

1. Activate LAL either by moving the front panel toggle switch

DOWN to “Local”, or; by raising the appropriate signal on

the DTE interface. Once Local Analog Loopback is

activated, the Model 1184/1185’s transmit output is connected

to its own receiver. The test LED should glow.

NOTE: Although the local Model 1184/1185 cannot communicate with the remote

Model 1185/1185 in this mode, the synchronized connection between the two

modems remains intact.

2. Verify that the data terminal equipment is operating properly

and can be used for a test. If a fault is indicated, call a

technician or replace the unit.

3. Perform a BER (bit error rate) test on each unit using a

separate BER tester. If the BER test equipment indicates no

faults but the data terminal indicates a fault, follow the

manufacturer's checkout procedures for the data terminal.

Also, check the interface cable between the terminal and the

Model 1184/1185.

5.3.2 Remote Digital Loopback

The Remote Digital Loopback test checks the performance of both

the local and remote Model 1184/1185,

and

the communication link

between them. Any characters sent to the remote unit in this test mode

will be returned back to the originating device (see Figure 7).

To perform an DL test, follow these steps:

1. Activate DL. This may be done in one of two ways: First, by

moving the front panel toggle switch DOWN to “Remote”. Or,

second, by raising the DL signal on the terminal interface (for

pin numbers, see Appendix D).

2. Perform a BER (bit error rate) test on the system, using BER

testers on both ends.

3. If the BER test equipment indicates a fault and the Local

Analog Loopback test was successful for both Model 1184 or

1185s, you may have a problem with the line between the

units. You should inspect the line for proper connections.

Figure 7. Remote Digital Loop

Figure 7. Local Analog Loopback

Local Model 1184/1185