Fluke Biomedical 945A - Manual (Page 31)

Auto Zero Mode
The contents of the auto zero counter, in the preamplifier, may be displayed at any time by placing the
UDR function switch to position 8. The display shows the current value of the counter and is updated
about once per second.
All units flash once per second as long as data is being received from the preamplifier. If a
communications break occurs, the units will stop flashing.
All alarms and error codes are inhibited except E0007 (loop fail).
The bargraph is blanked and the analog outputs are at low scale while the auto zero counter is displayed.
Refer to "Auto Zero Failure" and "Auto Zero Set-Up" for more information on the Auto Zero Mode.
Loop Test Mode
The functioning of the preamplifier communications loop can be tested by looping +TX and -TX back to
+RX and -RX on the UDR P2 connector and setting the UDR FUNCTION switch to position 9. While
executing the loop test, the bargraph will light (green) from left to right as characters are sent. The
numeric display will be blanked. If the test fails, the display will show E0009 and the bargraph will be red.
This test verifies proper operation of the UDR transmit/receive function, and may be used to determine if
the source of a communications error is in the UDR or the preamplifier.
The test runs continuously until the UDR FUNCTION switch is moved out of position 9.
All alarms are inhibited and the analog outputs are at low scale while the loop test is running.
There is an available device as part of the 942 Test Set for use with loop tests (P/N 942TS-100-45) that is
plugged into P2 to perform the interconnection function.
Alarms
The alarm functions provided by the UDR include HIGH, WARN, FAIL, and RANGE. The HIGH, WARN ,
and FAIL alarms drive relay contact outputs. Some operating modes of the UDR disable alarms. The
user is cautioned to read and fully understand section 4.
Alarm Logic
Alarm logic defines whether alarm relay coils are energized or de-energized in normal operation.
Standard alarm reset logic for the UDR is manual reset for the HIGH, and WARN alarms, and auto reset
for the FAIL and RANGE alarm.
Auto reset for HIGH and WARN alarms may be selected by jumper JP3-3.
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