viAssertTrigger

NI-VISA 15.0 Help

Edition Date: June 2015

Part Number: 370131S-01

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Purpose

Asserts software or hardware trigger.

C Syntax

ViStatus viAssertTrigger(ViSession vi, ViUInt16 protocol)

Visual Basic Syntax

viAssertTrigger&(ByVal vi&, ByVal protocol%)

Resource Classes

GPIB INSTR, GPIB INTFC, PXI INSTR, PXI BACKPLANE, Serial INSTR, TCPIP INSTR, TCPIP SOCKET, USB INSTR, USB RAW, VXI INSTR, VXI BACKPLANE

Parameters

Name Direction Description

vi

IN

Unique logical identifier to a session.

protocol

IN

Trigger protocol to use during assertion. Valid values are:

 Range

 GPIB, Serial, TCPIP, USB

 VI_TRIG_PROT_DEFAULT (0)

 VXI

 VI_TRIG_PROT_DEFAULT (0),
 VI_TRIG_PROT_ON (1),
 VI_TRIG_PROT_OFF (2), and
 VI_TRIG_PROT_SYNC (5)

 PXI

 VI_TRIG_PROT_RESERVE (6)
 VI_TRIG_PROT_UNRESERVE (7)

Return Values

Completion Codes Description

VI_SUCCESS

The specified trigger was successfully asserted to the device.

Error Codes Description

VI_ERROR_INV_OBJECT

The given session reference is invalid.

VI_ERROR_NSUP_OPER

The given vi does not support this operation.

VI_ERROR_RSRC_LOCKED

Specified operation could not be performed because the resource identified by vi has been locked for this kind of access.

VI_ERROR_INV_PROT

The protocol specified is invalid.

VI_ERROR_TMO

Timeout expired before operation completed.

VI_ERROR_RAW_WR_PROT_VIOL

Violation of raw write protocol occurred during transfer.

VI_ERROR_RAW_RD_PROT_VIOL

Violation of raw read protocol occurred during transfer.

VI_ERROR_INP_PROT_VIOL

Device reported an input protocol error during transfer.

VI_ERROR_BERR

Bus error occurred during transfer.

VI_ERROR_LINE_IN_USE

The specified trigger line is currently in use.

VI_ERROR_NCIC

The interface associated with the given vi is not currently the controller in charge.

VI_ERROR_NLISTENERS

No-listeners condition is detected (both NRFD and NDAC are unasserted).

VI_ERROR_INV_SETUP

Unable to start operation because setup is invalid (due to attributes being set to an inconsistent state).

VI_ERROR_CONN_LOST

The I/O connection for the given session has been lost.

Description

The viAssertTrigger() operation sources a software or hardware trigger dependent on the interface type.

Software Triggers for 488.2 Instruments (GPIB, VXI, TCPIP, and USB)

This operation sends an IEEE-488.2 software trigger to the addressed device. For software triggers, VI_TRIG_PROT_DEFAULT is the only valid protocol. The bus-specific details are:

  • For a GPIB device, VISA addresses the device to listen and then sends the GPIB GET command.
  • For a VXI device, VISA sends the Word Serial Trigger command.
  • For a USB device, VISA sends the TRIGGER message ID on the Bulk-OUT pipe.

Software Triggers for Non-488.2 Instruments (Serial INSTR, TCPIP SOCKET, and USB RAW)

If VI_ATTR_IO_PROT is VI_PROT_4882_STRS, this operations sends "*TRG\n" to the device; otherwise, this operation is not valid. For software triggers, VI_TRIG_PROT_DEFAULT is the only valid protocol.

Hardware Triggering for VXI

For hardware triggers to VXI instruments, VI_ATTR_TRIG_ID must first be set to the desired trigger line to use; this operation performs the specified trigger operation on the previously selected trigger line. For VXI hardware triggers, VI_TRIG_PROT_DEFAULT is equivalent to VI_TRIG_PROT_SYNC.

Trigger Reservation for PXI

For PXI instruments, this operation reserves or releases (unreserves) a trigger line for use in external triggering. For PXI triggers, VI_TRIG_PROT_RESERVE and VI_TRIG_PROT_UNRESERVE are the only valid protocols.


Related Topics

BACKPLANE Resource

INSTR Resource

INTFC Resource

SOCKET Resource

VI_ATTR_TRIG_ID

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