VISA viOpen
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Schema
Description
The viOpen() operation opens a session to the specified resource. It returns a session identifier that can be used to call any other operations of that resource. The address string passed to viOpen() must uniquely identify a resource.
Input Pins
- viInterface
The handle to the visa interface - rmSession
The resource manager session - resourceString
The visa identifier of the device (see remarks) - accessMode
The mode how the device should be accessed - timeout
Timeout for opening the device
Output Pins
- viOpenInterface
The handle to the device
Remarks
ResourceString
The resourceString ist the Identifier for VISA to select the proper device you want to connect to. You can check the resourceString if you select the device in the NI Measurement & Automation Explorer and select the Tab VISA properties. Then you can see the resourceString on the top. If you specify an VISA alias it should be also possible to use it as resourceString.
VI_ATTR_RSRC_NAME is the unique identifier for a resource compliant with the address structure shown in the following table. Optional string segments are shown in square brackets.
Interface Syntax
GPIB INSTR GPIB[board]::primary address[::secondaryaddress][::INSTR] GPIB INTFC GPIB[board]::INTFC GPIB SERVANT GPIB[board]::SERVANT GPIB-VXI INSTR GPIB-VXI[board]::VXI logical address[::INSTR] GPIB-VXIBACKPLANE GPIB-VXI[board][::mainframe logical address]::BACKPLANE GPIB-VXIMEMACC GPIB-VXI[board]::MEMACC PXI INSTR PXI[bus]::device[::function][::INSTR] PXI INSTR PXI[interface]::[bus-]device[.function][::INSTR] PXI MEMACC PXI[interface]::MEMACC Serial INSTR ASRL[board][::INSTR] TCPIP INSTR TCPIP [board]::host address[::LAN device name][::INSTR] TCPIP SOCKET TCPIP [board]::host address::port::SOCKET USB INSTR USB[board]::manufacturer ID::modelcode::serial number[::USBinterfacenumber][::INSTR] USB RAW USB[board]::manufacturer ID::modelcode::serial number[::USBinterfacenumber]::RAW VXI INSTR VXI[board]::VXI logical address[::INSTR] VXI BACKPLANE VXI[board][::mainframe logical address]::BACKPLANE VXI MEMACC VXI[board]::MEMACC VXI SERVANT VXI[board]::SERVANT
AccessMode
The mode specifies the VISA Access Mode. It can have the following values:
0 = VI_NO_LOCK 1 = VI_EXCLUSIVE_LOCK 2 = VI_SHARED_LOCK
For the parameter accessMode, the value VI_EXCLUSIVE_LOCK (1) is used to acquire an exclusive lock immediately upon opening a session; if a lock cannot be acquired, the session is closed and an error is returned. The value VI_LOAD_CONFIG (4) is used to configure attributes to values specified by some external configuration utility. Multiple access modes can be used simultaneously by specifying a bit-wise OR of the values other than VI_NULL. NI-VISA currently supports VI_LOAD_CONFIG only on Serial INSTR sessions.
Revisions
These blocks have been in the VISA Interface Library since 1.0.
Back to VISA Interface Library.
Previous: VISA [ Open Interface ]
Next: VISA [ viOpenDefaultRM ]
