MDO3000 Programmer Manual.pdf - 第106页

Command Groups T rigger Comma nd Group Use the commands in the Trigger Command Group to control all aspects of triggering the oscilloscope. Y ou can perform edge, pulse width, logic, vi deo, runt, timeout, tra nsition (r…

Command Groups

Table 2-39: Search Commands (cont.)

Command Description

SEARCH:SEARCH<x>:TRIGger:A:UPPerthreshold:

RF_FREQuency

For a runt or transition search using the RF Frequency vs. Time

trace, this command speciﬁes the upper threshold to be used by

the search engine.

SEARCH:SEARCH<x>:TRIGger:A:UPPerthreshold:

RF_PHASe

This command speciﬁes the upper threshold to be used by the

search engine when performing a runt or transition search using

the RF Phase vs. Time trace.

Status and Error C om mand Group

Use the commands in the Status and Error Command Group to determine the

status of the oscilloscope and control events.

Several commands and queries used with the oscilloscope are common to all

IEEE488.2 compliant devices. The IEEE Std 488.2-1987 deﬁnes these commands

and queries. The common commands begin with an asterisk (*) character.

Table 2-40: Status and E rror Commands

Comma

Description

ALLE

Returns all events and their messages

BUSY

Returns oscilloscope status

*CL

Cle

ars status

DES

Thi

s command speciﬁes the bits in the Device Event Status Enable Register

is command speciﬁes the bits in the Event Status Enable R egister

ESR?

eturns the contents of the Standard Event Status Register

VENT?

eturns event code from the event queue

EVMsg? Returns event code, message from the event queue

EVQty? Return number of events in the event queue

*OPC Generates the operation complete m essage in the standard event status register when all

pending operations are ﬁnished

Or returns "1" when all current operations are ﬁnished

*OPT? Returns a comma-separated list of installed options (not to be confused with

application modules) as an arbitrary ASCII string.

*PSC This command speciﬁes the power on status ﬂag

*PUD This command speciﬁes a string of protected user data

*RST Resets the o scilloscope to factory default settings

*SRE This command speciﬁes the bits in the Service Request Enable Register

*STB? Returns the contents of the Status Byte Register

*WAI Prevents the oscilloscope from executing further commands until all pending operations

ﬁnish

MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual 2-75

Command Groups

Trigger Comma

nd Group

Use the commands in the Trigger Command Group to control all aspects of

triggering the oscilloscope. You can perform edge, pulse width, logic, video, runt,

timeout, tra

nsition (rise/fall time), setup & hold and bus triggering using the A

trigger. You can perform sequence edge triggering using the A and B triggers.

The MDO4000/B/C allows you to use a change in the RF power level as a source

for edge triggering. Using an MDO4000/B/C oscilloscope with a MDO4TRIG

application module installed, a changeintheRFpowerlevelcanalsobeusedasa

source for pulse width, timeout, runt, logic and sequence triggers.

With the MDO4000/B/C, the acquisition system is fully integrated with boththe

time and frequency domain channels. This means

that a single event triggers

all of the analog, digital and RF acquisitions, regardless of where that trigger

event came from.

NOTE. MDO3000 models only have two digital threshold controls: o ne for d igital

channels D0 - D7, and the other for D8 - D15. Digital channel trigger levels

cannot be set independently for these models. Changing one digital channel’s

threshold level changes all of the channels

’ levels in the same set.

Example command sequences that show different triggers and searches are

available. (See page F-1, Search and Trigg

er Command Sequence Examples.)

Edge Trigger

Edge triggering lets you display a waveform at or near the point where the signal

passes through a voltage level of your choosing.

To set up an edge trigger, set the A trigger type to

EDGe using the command

TRIGger:A:TYPe. Then use the commands TRIGger:A:EDGE:COUPling,

TRIGger:A:EDGE:SLOpe,andTRIGger:A:EDGE:SOUrce You can

set the threshold voltage levels using TRIGger:A:LEVel:AUXin,

TRIGger:A:LEVel:CH<x>,orTRIGger:A:LEVel:D<x>.

Using an MDO4000/B/C oscilloscope, you can use the RF power level as a source

in an edge trigger without installing an MDO4TRIG application module. To do

this, set the oscilloscope to trigger on a rising edge with the RF power levelasthe

source, in order to trigger on events where the RF turns on. Conversely, set it to

trigger on a falling edge in order to trigger on events where the RF turns off.

Logic Trigger

Logic triggering lets you logically combine the signals on one or more channels;

the oscilloscope then triggers when it detects a certain combination of signal

levels (set using one of the

TRIGger:A:LOGIc:INPut commands as well as

TRIGger:A:LOGIc:FUNCtion). Using an MDO4000/B/C oscilloscope with an

MDO4TRIG application module installed, you can use the RF power level as a

source in a logic trigger.

2-76 MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual

Command Groups

To set up a logic

trigger, ﬁrst set the trigger type to

LOGIc using the command

TRIGger:A:TYPe, and then use the command TRIGger:A:LOGIc:CLAss to

select

LOGIC.

You can perform logic triggering using a clock (by setting TRIGger:A:LOGIc:

INPut:CLOCk:SOUrce to one of the channels), so that the oscilloscope triggers

when the speciﬁed logical combination of data channels is true during a

transition on the clock channel. The speciﬁed data sources cannot include the

waveform speciﬁed as the clock source. (Use TRIGger:A:LOGIc:INPut:CH<x>,

TRIGger:A

:LOGIc:INPut:D<x>,etc.)

You can also perform logic triggering without using a clock (by

setting T

RIGger:A:LOGIc:INPut:CLOCk:SOUrce to

NONE), so that the

oscilloscope triggers when the speciﬁed logical pattern of data channels

is met. (Use the commands TRIGger:A:LOGIc:PATtern:WHEn and

TRIGger:A:LOGIc:PATtern:DELTatime.)

Setup and Hold Trigger

A setup and hold trigger occurs when a logic data input changes state inside of the

setup or hold time relative to a clock edge.

To set up a setup/hold trigger, ﬁrst set the trigger type to

LOGIc using the command

TRIGger:A:TYPe, and then use the command TRIGger:A:LOGIc:CLAss

to select

SETHold.ThenuseTRIGger:A:SETHold:DATa:SOUrce,

TRIGger:A:SETHold:CLOCk:SOUrce, TRIGger:A:SETHold:CLOCk:EDGE

and related commands.

Pulse width Trigger

A pulse width trigger occurs whenever the oscilloscope detects a pulse thatis

less than, greater than, equal to, or not equal to a speciﬁed time. Additionally,

it can occur when the pulse width is within, or outside of a speciﬁed range.

ou can trigger on either positive or negative pulses. Using an MDO4000/B/C

oscilloscope with an MDO4TRIG application module installed, you can use the

RF power level as a source in a pulse width trigger.

To set up a pulse width trigger, ﬁrst set the trigger type to

PULSe using

the command TRIGger:A:TYPe. Then select

WIDth using the command

TRIGger:A:PULse:CLAss.ThenuseTRIGger:A:PULSEWidth:SOUrce,

TRIGger:A:PULSEWidth:WHEn, TRIGger:A:PULSEWidth:WIDth and related

commands. You can set the threshold voltage levels using TRIGger:A:LEVel:

AUXin, TRIGger:A:LEVel:CH<x>,orTRIGger:A:LEVel:D<x>.

Runt Trigger

Runt triggering lets you trigger on a pulse amplitude that crosses one threshold

but fails to cross a second threshold before recrossing the ﬁrst. Using an

MDO4000/B/C oscilloscope with an MDO4TRIG application module installed,

you can use the RF power level as the source in a runt trigger.

MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual 2-77