Agilent Technologies 6813B Generating Measurement Triggers, Pre-eventand Post-eventTriggering

Programming Examples - 4

To select GPIB bus triggers (group execute trigger, device trigger, or *TRG command), use:

TRIGger:SEQuence3:SOURce BUS or

TRIGger:ACQuire:SOURce BUS

To select the signal driving the Trigger Out BNC connector, use:

TRIGger:SEQuence3:SOURce TTLTrg or

TRIGger:ACQuire:SOURce TTLTrg

Generating Measurement Triggers

Providing that you have specified the appropriate trigger source, you can generate triggers as follows:

υBy sending one of the following over the GPIB:

TRIGger:SEQuence3:IMMediate

TRIGger:ACQuire:IMMediate

*TRG

a group execute trigger

υBy applying a signal with a high-to-low transition to the Trig In BNC connector.

υBy generating an output transient that causes the Trig Out BNC connector to output a pulse.

υBy pressing the front panel Trigger key when the unit is operating in local mode.

Controlling the Instantaneous Voltage and Current Data Buffers

Varying the Voltage and Current Sampling Rate

At *RST, the output voltage and current sampling rate is 40kHz (period = 25 μs). This means that it takes about 100 milliseconds to fill up 4096 data points in the voltage and current data buffers with the information required to make a measurement calculation. You can vary this data sampling rate with:

SENSe:SWEep:TINTerval <sample period>

The sample period can be programmed from a minimum period of 25 microseconds (the default), to 250 microseconds in 25 microsecond steps.

Pre-event and Post-event Triggering

The ac source continuously samples the instantaneous output voltage and current. While this is happening, you can move the block of data that is being read into the voltage and current buffers with respect to the data acquisition trigger. This permits pre-event or post-event data sampling. To offset the starting point of the data buffer relative to the acquisition trigger, use:

SENSe:SWEep:OFFSet:POINts <offset>

The range for this offset is 4096 to 2E9 points. As shown in the following figure, when the offset is negative, the values at the beginning of the data record represent samples taken prior to the trigger. When the value is 0, all of the values are taken after the trigger. Values greater than zero can be used to program a delay time from the receipt of the trigger until the data points that are entered into the buffer are valid. (Delay time = Offset X Sample period).

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