MDO3000 Programmer Manual.pdf - 第65页

Command Groups Math Command G roup Use the commands in the Math Command Group to create and deﬁne a math waveform. First, specify the math type using MA TH[1]:TYPe – either dual wavefor m, FFT , advanced math, or spectru…

Command Groups

Table 2-31: Mask commands (cont.)

Command

Description

MASK:USER:TRIGTOSAMP Speciﬁes the nominal time, in seconds, from the (leading edge) trigger position to the pulse

bit sampling position, to be used for testing with a user-deﬁned custom mask.

MASK:USER:VOFFSet Speciﬁes the nominal value, in volts, to be used to vertically offset the input channels

for a user-deﬁ ned custom m a sk.

MASK:USER:VPOS Speciﬁes the nominal value, in divisions, to be used to vertically position the input channels

for a user-deﬁ ned custom m a sk.

MASK:USER:VSCAle Speciﬁes the nominal value, in volts per division, to be used to vertically scale the input

channels for a user-deﬁned custom mask.

MASK:USER:WIDth Speciﬁes the nominal bit width value, in seconds, to b e used for a user-deﬁned custom

mask.

RECAll:MASK This command recalls the mask from a speciﬁed ﬁle that was saved to the current working

directory using the SAVe:MASK command.

SAVe:MASK This command saves the current mask deﬁ nition to the ﬁle speciﬁed with a quoted string,

into the current working directory. You can recall the mask from the ﬁle by using the

command RECAll:MASK.

2-34 MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual

Command Groups

Math Command G

roup

Use the commands in the Math Command Group to create and deﬁne a

math waveform. First, specify the math type using MATH[1]:TYPe – either

dual wavefor

m, FFT, advanced math, or spectrum math. Then, using the

MATH[1]:DEFine command, you can build simple math expressions that

contain no computation, such as

:MATH:DEFine CH1. You can also build

complex expressions that consist of up to 128 characters in a quoted string,

and comprise many sources, functions, and operands, such as

:MATH:DEFINE

"SINE(CH1)*(VAR1+CH2)*CH3 - CAREA(C H4)".

Note that when your program updates a live waveform or alters a reference

waveform, the math waveforms containing those waveforms as sources are also

updated

to reﬂect the changes.

NOTE. If you set the math type to

FFT

, your math expression can only be the

FFT of a live analog or reference waveform. However, if the math type is set

ADVanced

, then you can include FFT as part of a math expression. See the

examples of advanced math in MATH[1]:DEFine for more information.

Table 2-32: Math Commands

Command

Description

MATH[1]? Returns the deﬁnition of the m ath w aveform

MATH[1]:AUTOSCale Sets (or queries) the state o f automatic vertical scaling of the math waveform.

MATH[1]:DEF ine

This command speciﬁes the current math function as a text string.

MATH[1]:HO Rizontal:POSition This command speciﬁes the math horizontal display position for FFT or (non-live) math

reference waveforms

MATH[1]:HO Rizontal:SC Ale This command speciﬁes the math horizontal display scale for FFT or for Dual Math

waveforms

MATH[1]:HORizontal:UNIts Returns the math waveform horizontal unit value

MATH[1]:LABel

Sets or queries the waveform label for the math waveform

MATH[1]:SPECTral:MAG This command speci ﬁes the units of spectral magniﬁcation in the math string

MATH[1]:SPECTral:WINdow This command speciﬁes the window function for math waveform spectral input data

MATH[1]:TYPe

This command speciﬁes the math waveform type (

DUAL, FFT, ADVanced or

SPECTRUM

). This command is used along with MATH :DEFine.

MATH[1]:VERTical:POSition This command speciﬁes the vertical position of the currently selected math type

MATH[1]:VERTical:SCAle This command speciﬁes the vertical scale of the currently selected math type

MATH[1]:VERTical:UNIts

Returns the math wav e form vertical units

MATHVAR?

Returns all numerical values used within math expressions

MATHVAR:VAR<x>

This command speciﬁes numerical values you can use within math expressions

MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual 2-35

Command Groups

Measurement C

ommand Group

Use the commands in the Measurement Command Group to control the automated

measurement system.

Up to eight automated measurements can be displayed on the screen. In the

commands, these measurement readouts are named MEAS<x>, where <x> is the

measurement number.

In addition to the eight displayed measurements, the measurement commandslet

you specify an additional measurement, IMMed. The immediate measurement

has no front-panel equivalent. Immediate measurements are never displayed.

Because they are computed only when needed, immediate measurements slow the

waveform update rate less than displayed measurements.

To obtain measurement results, use the MEASUrement:MEAS<x>:VALue?

query for displayed results or the MEASUrement:IMMed:VALue? query for

immediate measurements.

Measurement commands can set and query measurement parameters. You

can assign some parameters, such as waveform sources, differently for each

measurement. Other parameters, such as reference levels, have only one value,

which applies to all measurements.

Readout values for t

he 8 displayed measurements are updated periodically. As

such, queries of these measurement values may return 9.91E+37, which represents

NaN (not a number) and a measurement warning event (e.g. 2225. “Measurement

error. No waveform to measure”) when the measurement is not yet computed.

Immediate measurement queries will return values once the measurement has

been computed.

Example of Immediate

Measurements

An example command sequence follows that illustrates immediate measurements

of Cycle Mean on channel 1:

:MEASUrement:IMMed:SOUrce1 CH1

:MEASUrement:IMMed:TYPe CMEan

:MEASUrement:IMMed:VALue? -18.5568E-3

:MEASUrement:IMMed:VALue?;VALue?;VALue?

-21.6400E-3;-23.8023E-3;-21.0064E-3

Table 2-33: Measurement Commands

Command

Description

MEASUrement?

Returns all measurement parameters

MEASUrement:CLEARSNapshot

Removes the measurement snapshot display

MEASUrement:GATing This command speciﬁes the measurement gating

MEASUrement:IMMed?

Returns all immediate measurement setup parameters

2-36 MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual