TRIGger:SOURce

TRIGger:SOURce

Syntax | Description | Parameters | Remarks | Return Format | Examples

Syntax

TRIGger:SOURce <source>

TRIGger:SOURce?

Description

Select the trigger source to control the onset of each sweep through the scan list (a sweep is one pass through the scan list). The instrument will accept a software (bus) command, an immediate (continuous) scan trigger, an external TTL trigger pulse, an alarm-initiated action, or an internally paced timer.

Used With:

• 34901A   20 Channel Multiplexer (2/4-wire) Module
• 34902A   16 Channel Multiplexer (2/4-wire) Module
• 34907A   Multifunction Module (digital input and totalizer channels only)
• 34908A   40 Channel Single-Ended Multiplexer Module

Parameters

Name	Type	Range of Values	Default Value
<source>	Discrete	{BUS| IMMediate | EXTernal | ALARm1| ALARm2 | ALARm3 | ALARm4 | TIMer} IMMediate = Continuous scan trigger BUS = Software trigger EXTernal = An external TTL pulse trigger ALARm = Trigger on an alarm TIMer = Internally paced timer trigger	This is a required parameter. The factory default is IMMediate.

Remarks

• For the IMMediate (continuous) source, the trigger signal is always present. When you place the instrument in the "wait-for-trigger" state, the trigger is issued immediately.
• The READ? and MEASure commands and queries cannot be used to take readings when the trigger source is BUS. This is called a trigger deadlock condition.
• For the BUS (software) source, the instrument is triggered by the *TRG command received over the remote interface. The *TRG command will not be accepted unless the instrument is in the "wait-for-trigger" state (see INITiate command). If the instrument receives an external trigger before the next "waiting for trigger" state, it will buffer one *TRG command and then ignore any additional triggers received (no error is generated).
• For the EXTernal source, the instrument will accept a hardware trigger applied to the rear-panel Ext Trig Input line (Pin 6). The instrument takes one sweep through the scan list each time a low-true TTL pulse is received. If the instrument receives an external trigger but is not in the "wait-for-trigger" state, it will buffer one trigger and then ignore any additional triggers received (no error is generated). Also, if the trigger source is BUS, you can use the scan button as a trigger.
• For the ALARmx source, the instrument is triggered each time a reading crosses an alarm limit on a channel. See the OUTPut:ALARm<n>:SOURce command for more information. With this source, you can use the Monitor mode (see ROUTe:MONitor:STATe command) to continuously take readings on a selected channel and wait for an alarm on that channel. Digital input and totalizer channels do not have to be part of the active scan list to be monitored.
• For the TIMer source, you control the trigger-to-trigger interval (in seconds) for measurements on the channels in the present scan list. Use the TRIGger:TIMer command to set the wait period.
• After selecting the trigger source, you must place the instrument in the "wait-for-trigger" state using the INITiate or READ? command. A trigger will not be accepted from the selected trigger source until the instrument is in the "wait-for-trigger" state.
• Although the TRIGger:SOURce command shares some of the same signals as the ROUTe:CHANnel:ADVance:SOURce command (used for external scanning), they cannot be set to the same source (except IMMediate). If you attempt to select the same source, an error is generated and the TRIGger:SOURce is reset to IMMediate.
• The CONFigure and MEASure? commands automatically set the trigger source to IMMediate.
• The instrument selects the immediate trigger source after a Factory Reset (*RST command). An Instrument Preset (SYSTem:PRESet command) or Card Reset (SYSTem:CPON command) does not change the setting.

Return Format

The query returns the trigger source as "BUS", "IMM", "EXT", "ALAR1", "ALAR2", "ALAR3", "ALAR4", or "TIM".

Examples

The following program segment selects the external trigger source. In this configuration, the instrument sweeps through the scan list once each time a low-true TTL pulse is received on the rear-panel Ext Trig Input line (Pin 6).

TRIG:SOUR EXT
INIT

 

The following program segment selects the bus (software) trigger source. Note that the *TRG command will not be accepted unless the internal DMM is in the "wait-for-trigger" state.

TRIG:SOUR BUS
INIT
*TRG

 

The following program segment selects the alarm source and configures the instrument to scan when an alarm is reported on Alarm 1. The Monitor mode is used to evaluate alarm conditions on the selected channel.

ROUT:SCAN (@103)              !Set the scan list to a single channel
TRIG:SOUR ALARM1              !Select trigger source
OUTP:ALAR:SOUR (@103)
CALC:LIM:UPP 10.25,(@103)     !Set upper alarm limit
CALC:LIM:UPP:STAT ON,(@103)   !Enable alarms
ROUT:MON (@103)               !Select monitor channel
ROUT:MON:STAT ON              !Enable monitor mode
INIT

 

The following program segment selects the timer source and sets the scan interval to 30 milliseconds.

TRIG:SOUR TIMER                !Select trigger source
TRIG:TIM 30E-03                !Scan interval is 30 ms
INIT

 

The following query returns the trigger source currently selected.

TRIG:SOUR?

Typical Response: EXT

See Also

TRIGger Subsystem Introduction

*TRG

OUTPut:ALARm{1|2|3|4}:SOURce

ROUTe:CHANnel:ADVance:SOURce

ROUTe:MONitor:STATe

TRIGger:TIMer