:MEASure:EYE:FALLtime

Meas. mode:
Eye
Waveform type:
NRZ
Flex Apps:
FlexDCA
FlexRT
Fall Time Commands

Command Syntax

:MEASure:EYE:FALLtime

Query Syntax

:MEASure:EYE:FALLtime?

Description

Moves the Fall Time measurement to the top of the Results table. Displays the measurement if it is not already shown on the table. The query form of the command returns the measured value. Fall Time is a measure of the mean transition time of the data on the downward slope of an eye diagram. The data crosses through the following three data thresholds: the upper, middle, and lower thresholds, as well as through the eye crossing points. The default setting for the threshold levels are the 10% to 90% points on the transition. Sources can be any displayed waveform, color-grade memory, or function. For example, CHAN1A, CGMemory1, or FUNCtion1. Use the :MEASure:EBOundary:LEFT, :MEASure:EBOundary:RIGHt, and :MEASure:EBOundary:DEFault commands to change the eye boundary settings. Use :MEASure:TBASe:METHod to change the definition of the waveform's top/base. Use the :MEASure:THReshold:METHod command to change the definition of the waveform's threshold.

Measurement Identification

Avoid subtle programming errors! To ensure that the correct measurement is installed or queried, always explicitly identify a measurement when installing a measurement or querying a measured value, status, or detail. To identify a measurement, specify the measurement's source waveform (:SOURce child command). With some measurements, you may also need to specify other identifying values. Generally, when selecting a measurement using FlexDCA's GUI, if a dialog appears prompting you to select values, you should explicitly specify these values when remotely identifying the measurement. More information.

For example, to return the status of the measurement, :MEASure:EYE:FALLtime:

flex.write(':MEASure:EYE:FALLtime:SOURce CHAN1A')
if flex.query(':MEASure:EYE:FALLtime:STATus?') == 'CORR';
    measurement = flex.query(':MEASure:EYE:FALLtime?')
else:
	details = flex.query(':MEASure:EYE:FALLtime:STATus:DETails?')
	reason = flex.query(':MEASure:EYE:FALLtime:STATus:REASon?')

Child commands for measurement identification:

  • :MEASure:EYE:FALLtime:SOURce

This Eye mode measurement can be applied to NRZ waveforms but not PAM4 waveforms.

Example Command Sequence

:MEASure:EYE:FALLtime:SOURce CHAN1A
:MEASure:EYE:FALLtime
:MEASure:EYE:FALLtime?

Measurement Ready?

To confirm that the measurement is ready to read, you can query the measurement's status:

if ('CORR' in Flex.query(':MEASure:EYE:FALLtime:STATus?')):
	measurement = Flex.query(':MEASure:EYE:FALLtime?')

If averaging is turned on (:ACQuire:AVERaging), you can also confirm if the measurement result is ready by comparing the number of specified averages (:ACQuire:ECOunt?) versus the number of measurement sweeps that have occurred (:MEASure:EYE:FALLtime:COUNt?). The technique uses the :COUNt? common measurement query. For example,

if (Flex.query(':MEASure:EYE:FALLtime:COUNt?') >= Flex.query(':ACQuire:ECOUNt?')):
	measurement = Flex.query(':MEASure:EYE:FALLtime?')

You can also use an acquisition limit lest to test that a number of waveform samples, or pattern acquisitions have completed before returning a measurement. Refer to the :LTESt:ACQuire:CTYPe command.

Common Measurement Child Queries

This command supports the use of the following common measurement queries: :LOCation?, :COUNt?, :MAXimum?, :MINimum?, :MEAN?, and :SDEViation?.