MDO3000 Programmer Manual.pdf - 第33页

Command Syntax Queries Queries c ause t he oscilloscope to return status or setting information. Queries have the structure: [:]<Header> [:]<Header>[<Spa ce><Argument> [<Comma><Argu ment&…

Command Syntax

Table 2-2: Comm

and Message Elements

Symbol Meaning

This is the basic command name. If the header ends with a question

mark, the command is a query. The header may begin with a colon

(:) c haracte

r. If the command is concatenated with other commands,

the beginning colon is required. Never use the beginning colon with

command headers beginning with a star (*).

This is a header subfunction. Some command headers have only one

mnemonic. I

f a command header has multiple mnemonics, a colon (:)

character always separates them from each o ther.

<Argument

This is a qu

antity, quality, restriction, or limit associated with the header.

Some commands have no arguments while others have multiple

arguments. A <space> separates arguments from the header. A

<comma> se

parates arguments from each other.

<Comma> A single c

omma is used between arguments of multiple-argument

commands. Optionally, there may be white space characters before

and after the comma.

<Space>

A white space character is used between a command header and the

related argument. Optionally, a wh ite space may consist of multiple

white sp

ace characters.

Commands

Comman

ds cause the oscilloscope to perform a speciﬁc function or change one of

the settings. Commands have the structure:

[:]<H

eader>[<Space><Argument>[<Comma> <Argument>]...]

A command header consists of one or more mnemonics arranged in a hierarchical

or tr

ee structure. The ﬁrst mnemonic is the base or root of the tree and each

subsequent mnemonic is a level or branch off the previous one. Commands at a

higher level in the tree may affect those at a lower level. The leading colon (:)

always returns you to the base of the command tree.

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

Command Syntax

Queries

Queries cause t

he oscilloscope to return status or setting information. Queries

have the structure:

[:]<Header>

[:]<Header>[<Space><Argument> [<Comma><Argument>]...]

You can specify a query command at any level within the command tree unless

otherwise noted. These branch queries return information about all the mnemonics

below the speciﬁed branch or level.

Headers

Use the HEADer command to control whether the oscilloscope returns headers as

part of the query response. If header is on, the query response returns command

headers, then formats itself as a valid set command. When header is off, the

response includes only the values. This may make it easier to parse and extract the

information from the response. The table below shows the difference in responses.

Table 2-3: Comparison of Header Off and Header On Responses

Query Header Off Header On

TIME?

14:30:00 :TIME “14:30:00”

ACQuire:NUMAVg?

100

:ACQUIRE:NUMAVG 100

Clearing the oscilloscope

You can clear the Output Queue and reset the oscilloscope to accept a new

command or query by using the selected Device Clear (DCL) function.

Command Entry

The following rules apply when entering commands:

You can enter commands in upper or lower case.

You can precede any command with white space characters. White space

characters include any combination of the ASCII control characters 00 through

09 and 0B through 20 hexadecimal (0 through 9 and 11 through 32 decimal).

The oscilloscope ignores commands consisting of any combination of white

space characters and line feeds.

MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual 2-3

Command Syntax

Abbreviating

You can abbrevi

ate many oscilloscope commands. Each command in this

documentation shows the minimum acceptable abbreviations in capitals. For

example, you can enter the command

ACQuire:NUMAvg simply as ACQ:NUMA

or acq:numa.

Abbreviation rules may change over time as new oscilloscope models are

introduced. Thus, for the most robust code, use the full spelling.

If you use the HEADer command to have command headers included as part

of query responses, you can further control whether the returned headers are

abbreviated or are full-length with the

VERBose command.

Concatenating

You can concatenate any combination of set commands and queries using a

semicolon (;). The oscilloscope executes concatenated commands in the order

received.

When concatenating commands and queries, you must follow these rules:

1. Separate completely different headers by a semicolon and by the beginning

colon on all commands except the ﬁrst one. For example, the commands

TRIGger:MODe NORMal and ACQuire:N UMAVg 8, can be concatenated

into the following single command:

TRIGger:MODe NORMal;:A CQuire:NUMAVg 8

2. If concatenated commands have headers that differ by only the last mnemonic,

you can abbreviate the second command and eliminate the beginning colon.

For example, you can concatenate the commands

ACQuire:MODe ENVelope

and ACQuir e:NUMAVg 8 into a single command:

ACQuire:MODe ENVelope; NUMAVg 8

The longer version works equally well:

ACQuire:MODe ENVelope; :ACQuire:NUMAVg 8

3. Never precede a star (*) command with a colon:

ACQuire:STATE 1;*OPC

Any commands that follow will be processed as if the star command was

not there so the commands,

ACQuire:MODe ENVel

ope;*OPC;NUMAVg 8

will set the acquisition mode to envelope and set the number of acquisitions

for averaging to 8.

4. When you concatenate queries, the responses to all the queries are

concatenated into a single response message. For example, if the display

graticule is set to Full and the display style is set to dotsonly, the concatenated

query

DISplay:GRAticule?;STYle:DOTsonly? will return the following.

If the header is on:

DISPLAY:GRATICULE FULL;:DISPLAY:STYLE:DOTSONLY 1

2-4 MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual