MDO3000 Programmer Manual.pdf - 第129页

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 o f the associated settings for the waveform preambl…

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

Command Groups

NOTE. The

WFMIn

pre:BYT_Nr

and

WFMInpre:BI T_Nr

settings are directly

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

WFMInpre:B YT_Nr 2

causes

WFMInpre_B IT_Nr

tobesetto16(2*8bits/byte).

Similarly, setting

WFMInpre:BIT _Nr

to 16 causes

WFMInpre:B YT_Nr

to be

set to 2.

Table 2-45:

Example Command Sequence for Transferring Waveform Data from Computer to Oscilloscope

Item Descriptio

:DATa:DES

Tination REF2

Selects RE

F 2 as the internal reference memory location that the incoming

waveform will be transferred to.

:DATa:STARt 1 This, along with DATa:STOP, speciﬁes the starting and ending points of the

waveform record that will be transferred to REF2.

:DATa:STOP

10000

:WFMInpre:DOMain TIMe Speci ﬁes that the data to be transferred is a time domain w aveform, and

therefo

re should be treated as integers (as opposed to a frequency domain

waveform, which uses ﬂoating point).

:WFMIn

pre:BYT_Nr 1

Sets the number of bytes per data point in the waveform data to be sent

to RE F2 to 1.

:WFMInpre:BIT_Nr 8

Sets the number of bits per binary data point to 8.

:WFMInpre:ENCdg ASCII Speciﬁes that the incoming waveform uses the A SCII format.

:WFMInpre:NR_Pt 10000

Sets the number of data points that are being sent to REF2 to 10000.

:WFMInpre:PT_Fmt Y

Speciﬁes that the incoming waveform is a normal one, where one ASCII

or b

inary data point is transmitted for each point in the waveform record

(as opposed to envelope).

:WFMInpre:XUNit "S" Sets the horizontal units of the x-axis of the data points to seconds.

FMInpre:XINcr 4.0000E-9

Sets the horizontal interval between the incoming waveform points, using the

units speciﬁed above.

:WFMInpre:XZERo -20.0000E-6

Sets the position value of the ﬁrst data point in the incoming waveform record.

:WFMInpre:YUNit "V"

Speciﬁes that Volts are the v ertical units of the data points being sent.

:WFMInpre:YMUlt 4.0000E-3

Speciﬁes the vertical scale multiplying factor used to convert the incoming

data points from digitizing levels into the units speciﬁed above.

:WFMInpre:YOFf 0.0E+0 Speciﬁes that the vertical position in digitizing levels of the incoming reference

waveform is 0.

:WFMInpre:YZEro 0.0E+0

Speciﬁes that the vertical offset of the incoming waveform is 0.

:HEADer 1 Turning on HEADer and VERBose will allow the WFMInpre? parameters

to be viewed in context.

:VERBose 1

:WFMInpre? Do this query to verify your settings.

:CURVe <10,000 AS CIi data points, each separated

by a comma>

Sends the data points to REF2.

2-100 MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual