Checking the Trigger Source

Note

The TRIGger:SOURce? command returns “BUS”, “EXT”, “IMM”, or “TTLTnto show the present trigger source. The string is sent to the output buffer.

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 μs. 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.

Chapter 2

HP E1312A/E1412A Multimeter Application Information 47