HP 3478A Quick Reference Manual page 2

Function selections:
The function selections are controlled from the upper row of buttons and are as follows
(left to right)
DC Volts
AC volts
2 wire resistance
4 wire resistance
DC amps
AC amps
Below this row is a second row of buttons. The first is the auto range switch. When the
instrument is turned on initially it will be in auto range mode. This will change the
measurement range as needed by the incoming signal. There are times when it is
advantageous to have a continuous range setting. Pressing the auto/man button will
illuminate the 'M RNG' indicator on the display and place the unit in manual range
control. The up and down arrows will then adjust the range to your desired setting. The
next two buttons control the trigger mode of the meter.
Under normal circumstances a continuous trigger (INT TRIG) will provide for a
continuous update of the current value on the input connections. Some signals may
change or be short lived, necessitating the use of a single trigger mode. In this mode each
time the 'SGL TRIG' button is pressed it will take and hold one reading.
SRQ and LOCAL are used with external communications and can be ignored at this time.
At times it may be advantageous to limit the number of digits of resolution. Since
resolution and update speed have a direct correlation, a fast changing signal may be better
read with a 3, 4 of 5 digit resolution rather than the standard 6. To select this mode, press
the shift button and then the desired number of digits.
The meter automatically performs auto zero's on the input to keep internal float from
creeping into the readings. This mode can be turned off by selecting shift and AUTO
ZERO.
TEST/RESET function issues a display test and reset to default conditions. This is a
handy way to "clean up" from manual settings.
ADRS and CAL are unused for normal operations.
Input Connections:
This meter has two sets of input connections. The front panel connections and a second
set on the rear panel meant for permanent mounted operations. The TERM button on the
front switches between these two sets of input connectors and is a common place of
frustration. Make sure the switch is out for front panel operation.