HP E1429A manual ARM-TRIG State Diagram

The ARM-TRIG State Diagram

Note

The state diagram of Figure 3-4 shows that the digitizer operates within four states: idle, initiated, wait-for-arm, and wait-for-trigger. The path through the states depends upon whether pre-arm sampling is part of the measurement configuration.

Both paths begin with the digitizer in the idle state. The digitizer enters the idle state when power is applied, or following a reset or an ABORt. This is the state in which the digitizer is configured using CONFigure and its low-level commands.

When configuring the digitizer’s arming and triggering hardware the configuration applies to both digitizer channels. Thus, both channels enter the same Arm-Trigger state at the same time. In arming and triggering commands where a channel can be specified such as

SENSe[<chan >]:SWEep:OFFSet:POINts <count >

the configuration of the last channel specified (or implied) overrides the previous configuration of both channels.

The Pre-Arm Path The digitizer is capable of pre-arm and post-arm sampling. If pre-arm samples (readings) have been specified

(SENSe[<chan >]:SWEep:OFFSet:POINts <count >) in addition to post-arm samples, the digitizer moves to the wait-for-trigger state when INITiate[:IMMediate] is executed and begins sampling. The digitizer continues to (pre-arm) sample until the pre-arm reading count is reached and until the digitizer receives an arm signal. When the arm is received, the digitizer begins post-arm sampling as triggers are received. The digitizer continues to (post-arm) sample until the total number of samples (pre- and post-arm) specified by TRIGger[:STARt]:COUNt <count > is reached. Once the trigger count is reached, the digitizer determines if the arm count has been reached. If it has not, the digitzer remains initiated and repeats the path until the arm count is reached.

The Post-Arm Path When only post-arm samples are specified, the digitizer moves to the wait-for-arm state when INITiate[:IMMediate] is executed. The digitizer moves to the wait-for-trigger state when an arm signal is received. The digitizer remains in the wait-for-trigger state until the number of samples specified by TRIGger[:STARt]:COUNt <count > is reached. Once the trigger count is reached, the digitizer determines if the arm count has been reached. If it has not, the digitizer remains initiated and repeats the path until the arm count is reached.

112 Understanding the HP E1429 Digitizer Chapter 3