MDO3000 Programmer Manual.pdf - 第128页

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 1o r2 bytes, as signed or unsigned integers. DIGi…

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

Command Groups

sources, the fo

rmat is that for the RF frequency domain traces, which is 4-byte

ﬂoating point data.

NOTE. When you change the

DATa:SOUrc e

setting, all of the associated settings

for the waveform preamble (

WFMOutpre

commands) are automatically adjusted

for the speciﬁed source waveform. The speciﬁed source waveform must be turned

on.

Data Encoding and Widths. Data transferred from the oscilloscope using the

CURVe query can be sent in either ASCII or binary formats. ASCII data is sent as

a comma-separated list of decimal values. Binary data is sent with the IEEE488.2

binary block header, immediately followed by the binary data.

You can specify the format for waveform transfers from the oscilloscope

using the combination of

WFMOutpre:ENCdg, WFMOutpre:BN_Fmt and

WFMOutpre:BYT_Or commands. Or else you can simply use the DATa:ENCdg

comman

d, which combines all three.

ASCII data is represented by signed integer values for analog and digital

chann

els and by 4-byte ﬂoating point values for the RF frequency domain traces

(RF_NORMal, RF_AVErage, RF_MAXHold, RF_MINHold). The range of the

values depends on the data width (speciﬁed using the

WFMOutpre:BYT-Nr or

DATa:WIDth command). One byte wide data ranges from -128 to 127. Two byte

wide data ranges from -32768 to 32767. For digital channels D0 through D15, the

values returned are 0 or 1. For the Digital Collection, ASCII data is returned in

hex

adecimal format with any leading zeroes omitted.

Transferring a Waveform

from a Computer to an

Oscilloscope’s Internal

Reference Memory

Waveforms sent from a computer program TO the oscilloscope are always

stored in one of the internal reference memory locations (REF1-4). Use

Ta:DESTination

to specify the reference memory location, as well other

DATa commands to specify record start and stop points. Next, use the WFMInpre

commands to specify the waveform’s data format, scale, domain and other

attributes that will be used to convert raw data points into the scope's internal

waveform points. Then, use

WFMInpre? to verify your settings. Finally, use the

CURVe command to transfer the raw data points.

Following is an example command sequence that illustrates how to transfer

waveform data to the oscilloscope’s internal reference memory.

In this case, let’s say you have created a waveform on your computer and would

like to transfer 10,000 data points of it, in ASCii format with 1 byte per point, to

your oscilloscope’s internal reference memory location REF2.

MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual 2-99