HP 5890 Series II Plus Reference Manual page 91

Signal Output
HP-IL loopback test
Figure 5-12
HPIL LOOPBACK TEST Displays
The message PASSED SELF TEST indicates INET, at least with respect
to the HP 5890, is performing satisfactorily. If FAILED SELF-TEST is
displayed, a bad cable may be indicated; install a different INET cable
and repeat the test. If FAILED SELF-TEST is displayed again for a second
cable, electronic problems within the HP 5890 are indicated.
Note: The loopback test may be used to check for continuity in an
INET cable; an open cable causes test failure. Verify that the cable is at
fault (rather than the HP 5890) by testing a second cable.
If an intermittent cable problem is suspected, the test may be repeated as
necessary while flexing the cable (particularly at its plugs). An ohmmeter
should also be used to test for problems; it is a reliable method for testing
continuity.
HPIL LOOPBACK
PASSED SELF
FAILED SELF
ACTUAL SETPOINT
TEST
ACTUAL SETPOINT
TEST
ACTUAL SETPOINT
TEST
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