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HP E1312A/E1412A Multimeter Application Information 47Chapter 2
Checking the
Trigger Source
The TRIGger:SOURce? command returns “BUS”, “EXT”, “IMM”, or
“TTLTn” to show the present trigger source. The string is sent to the
output buffer.
Note Note that a CONFigure or MEASure? command automatically sets the
trigger source to
IMMediate. You must follow the CONFigure command
with the
TRIG:SOUR command to set the trigger source to BUS, EXTernal
or to TTLTrg<n>. The MEAS? command always uses TRIG:SOUR IMM.
External Triggering Use TRIGger:SOURce EXTernal to set the trigger source to external.
• The trigger signal must be a low-true pulse with a pulse width greater
than 1
µ
s. The trigger signal level accepted is TTL (+5V maximum
negative-going to 0V). See the following diagram for the “Trig” input
requirement. The diagram also shows the “VM Complete” output you
can use to synchronize with a switch module.
• The multimeter takes one reading (or the number specified by
SAMPle:COUNt) for each external trigger received on the front panel
“Trig” BNC connector.
Internal Triggering The trigger signal is always present in the internal triggering mode. This
mode is selected with the
TRIGger:SOURce IMMediate command.
• The multimeter takes one reading (or the number specified by
SAMPle:COUNt) immediately after a READ? or INITiate command.
The multimeter takes only one reading immediately following a
MEAS? command.
• See the triggering process diagram in Figure 2-1 on page 45.