MDO3000 Programmer Manual.pdf - 第127页

Command Groups T able 2 -44: Example Command Sequence for T ransferri ng Waveform Data from Oscilloscope to Computer (cont.) Item Description :HEADer 1 T urning on HEADer and VERBose will allow you to view the WFMOutpr e…

Command Groups

<binary data> i

s the binary data which should be exactly N-Digits bytes in

length.

NOTE. Ifyouwouldliketosaveorrecallawaveformtoorfromaﬁle, use the

SAVe:WAVEform and RECAll:WAVEform commands.

Transferring a Waveform

from an Oscilloscope to a

Computer

Use the DATa commands and WFMOutpre commands to specify the attributes of

the waveform being transferred from the oscilloscope. You must, at a minimum,

specify the waveform source (using the

DATa:SOUrce command) and data format

(using the

DATa:ENCdg and DATa:WIDth commands).

Then, use the

WFMOutpre? query, which provides the context needed to interpret

the waveform data points. Finally, use the

CURVE? query to transfer the waveform

data points. (You can also use the

WAVFrm? query, which concatenates the

WFMOutpre? and CURVe? queries. )

NOTE. In order to guarantee that the waveform data returned from

CURVE?

queries of multiple waveforms are correlated to the same acquisition, you

should use single sequence acquisition mode to acquire the waveform data

from a single acquisition. Single sequence acquisition mode is enabled using

ACQuire:STOPAfter

SEQuence

NOTE. The

WFMOutpre:BYT _Nr

and

WFMOutpre:BIT _Nr

settings are

directly related; setting one causes the other to be set accordingly. For

example,

WFMOutpre:BY T_Nr 2

causes

WFMOutpre_B IT_Nr

to be set to

16 (2 * 8 bits/byte). Similarly, setting

WFMOutpre: BIT_Nr

to 16 causes

WFMOutpre: BYT_Nr

to be set to 2.

Following is an example command sequence that illustrates how to transfer

waveform data from the oscilloscope to the computer.

In this case, let’s say you’d like to transfer 10,000 points from channel 1, in ASCii

format with 1 byte per point, to your computer program.

Table 2-44: Example Command Sequence for Transferring Waveform Data from Oscilloscope to Computer

Item Description

:DATa:SOUrce CH1 Sets the source waveform to be transferred to Channel 1.

:DATa:STARt 1 This, along with DATa:STOP, speciﬁes the portion of the w aveform record that will

be transferred .

:DATa:STOP 10000

:DATa:ENCdg ASCIi Sets the data format to ASCII. (This command replaces WFMOutpre:ENCdg,

WFMOutpre:BN_Fmt

and WFMOutp re:BYT_Or with a single command.)

:DATa:WIDth 1

Sets 1 byte per point (same as

WFMOutpre:BYT_Nr).

2-96 MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual

Command Groups

Table 2 -44: Example Command Sequence for Transferring Waveform Data from Oscilloscope to Computer (cont.)

Item Description

:HEADer 1 Turning on HEADer and VERBose will allow you to view the WFMOutpre?

parameters in context.

:VERBose 1

:WFMOutpre? The WFMO utpre? query provides the information needed to interpret the waveform

data point information that will be returned from the

CURVe query.

:HEADer 0

You may want to turn the header off before doing the

CURVe query, because w ith

the header on, a

CURVe query will return the CURVe command header followed by

a space and the ASCII waveform data.

:CURVe? Transfers the data points.

NOTE. Command sequence examples as well as sev eral comprehensive examples

of what the

WFMOutpre?

query might return using different data sources are

includ

ed as an appendix. (See page D-1, Waveform Transfer (WFMOutpre and

CURVe Query) Examples.)

Examp

le 1: Analog Waveform (channel 1 - 4)

Example 2: Digital Waveform (channel DO-D15)

Example 3: The Digital Collection with 4 Bytes Per Point with MagniVu Off

Example 4: The Digital Collection with 8 Bytes Per Point with MagniVu Off

Example 5: The Digital Collection with 4 Bytes Per Point with MagniVu On

Example 6: The Digital Collection with 8 Bytes Per Point with MagniVu On

ample 7: RF Frequency Domain Waveform

NOTE. Whenyoudoa

WFMOutpre?

query in an interactive session during

rogram development, it’s a good idea to ﬁrst turn on the header and verbose

features (using the

HEADer

and

VERBose

commands) in order to see the returned

values in context.

Waveform Sources. Valid waveform sources that can be transferred from the

oscilloscope (using the

DATa:SOUrce command) include:

CH1–CH4- Analog channels. When

DATa:SOUrce is set to one of these

sources, the data points represent digitizing levels. There are 25 digitizing levels

per vertical division for 1-byte data, and 6400 digitizing levels per vertical

division for 2-byte data. These data points can be transferred in signed or

unsigned integer formats.

D0 – D15 - The digital input channels (MSO/MDO4000/B models only as

well as MDO3000 and MDO4000C series models with options MDO3MSO or

MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual 2-97

Command Groups

MDO4MSO instal

led). When

DATa:SOUrce is set to one of these, the data points

are binary states (0 or 1). These data points can be transferred in widths of 1or2

bytes, as signed or unsigned integers.

DIGital - The Digital Collection. These data points are binary states (0 or 1) that

can be transferred in widths of 4 or 8 bytes, as signed or unsigned integers. For

ASCII encoding, the data is transferred as hexadecimal values with leadingzeroes

suppressed. When

DATa:SOUrce is set to DIGital, this represents a collection

of information that differs dependingonthedatawidth(setusingeitherthe

DATa:WIDt

or WFMOutpre:BYT_Nr command.)

When the data width is set to 4 bytes, the Digital Collection is the states of

digital c

hannels D0 – D15, plus the digital representations of analog channels

1 – 4, plus the trigger state.

When the

data width is set to 8 bytes, the Digital Collection is the transition

state information for digital channels D0 – D15, plus the digital representations

of analog channels 1 – 4. For more information, see the section below

“Further Explanation of Digital Collection Data”. (MSO/MDO4000/B models

only as well as MDO3000 and MDO4000C series models with options

MDO3MSO or MDO4MSO installed).

RF_NORMal, RF_AVErage, RF_MAXHold, RF_MINHold -thesearetheRF

frequency domain traces (MDO4000/B/C and MDO3000 models only). When

DATa

:SOUrce

is set to one of these traces, the data points represent the amplitude

of the trace in watts, and are ﬂoating point values. The frequency domain trace

data is returned as 4-byte ﬂoating point values. (Note that

CURVe? always returns

linear watts, not the display units.)

RF_AMPlitude, RF_FREQuency, RF_PHASe – these are the RF time domain

traces (MDO4000/B/C series models only.) When

DATa:SOUrce is set to one of

these traces, the data points are the Amplitude vs. Time, Frequency vs. Time, or

Phase vs. Time representations of the RF input signal.

The RF time domain traces are returned as 1-byte or 2-byte integers, depending

on the

DATa:WIDth setting. The default is 1 byte per point.

RF_FREQuency – frequency in Hz.

RF_PHASe – phase in degrees.

RF_AMPlitude – amplitude in Volts.

MATH — The format of MATH data is dependent upon the sources for the math

waveform. For analog channel sources, the format is that for the analog channels

described above. For spectrum math, the format is the same as for RF frequency

domain traces, which is 4-byte ﬂoating point data.

REF1-REF4 — The format of REF data is dependent upon the sources from

which the reference waveform was created. For analog channel sources, the

format is that for the analog channels described above. For RF frequency domain

2-98 MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual