Triggering the

Digitizer

TRIGger and SENSe Subsystems Overview

Setting the Trigger Source

After the digitizer is armed it enters the wait-for-trigger state. Thus, when trigger signals are received, the digitizer samples the inputs on its channels (Figure 3-5). The hardware associated with triggering the digitizer is controlled by the SCPI TRIGger subsystem, and by selected commands in the SENSe subsystem. The commands used in those subsystems include:

TRIGger [:STARtSEQuence[1]]

:COUNt <count > [:IMMediate] :SOURce <source > :TIMer1 <period > :TIMer2 <period >

[SENSe[<chan >]] :SWEep

:OFFSET

:POINts <count > :POINts <count >

The following information summarizes each command in the TRIGger subsystem and the two commands from the SENSe subsystem. The Command Reference (Chapter 4) contains detailed information on the parameter settings and on reset conditions.

The trigger source specifies the signal which triggers the digitizer to take a reading. The source is specified with the command:

TRIGger[:STARt]:SOURce <source >

The <source > parameters are:

BUS - HP-IB Group Execute Trigger (GET) commmand or the *TRG common command.

ECLTrg0/ECLTrg1 - the VXIbus ECLTRG0 or ECLTRG1 trigger lines.

TTLTrg<n > - the VXIbus TTLTRG0 through TTLTRG7 trigger lines.

EXTernal1 - the "Ext 1" input port.

EXTernal2 - the "Ext 2" input port.

HOLD - suspend triggering.

TIMer - sample rate is specified by the TRIGger:STARt:TIMer1 command. The rate is derived from a reference specified by the SENSe:ROSCillator subsystem. TIMer is the default trigger source.

VME - sample and/or transfer data from memory to the VME (VXI data transfer) bus when the data register at offset 12

( 0C16) in A24 address space is accessed.

Chapter 3

Understanding the HP E1429 Digitizer 121

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HP E1429A manual Triggering Digitizer, Offset