auto-discovery_address_check_and_vifindrsrc

If you are a VISA programmer, or you use applications developed with the VISA I/O library, you use the viFindRsrc and viFindNext functions to discover and list instruments in your test system. This topic explains the interactions between Agilent Connection Expert settings and viFindRsrc/viFindNext.

GPIB and LAN instruments have an address-check property, which can be set in Connection Expert. The scanning algorithm employed by viFindRsrc/viFindNext uses the address-check property to determine whether to scan for the instrument or to assume its presence. In addition, viOpen uses this property to decide whether to verify the presence of the instrument. Therefore,

• When address-check is on:
  
  
  • viFindRsrc/viFindNext will scan for an instrument at the given address. If the instrument is present and turned on, it will be discovered and returned by viFindRsrc/viFindNext. If the instrument is missing or nonfunctional (e.g., turned off), it will not be returned.
    
    
  • viOpen will verify the presence of the instrument on which you are trying to open a session.
     
• When address-check is off:
  
  
  •  viFindRsrc/viFindNext assume the presence of an instrument at that address. The instrument will be included in the returned values from  viFindRsrc/viFindNext regardless of whether the instrument is actually present.
      
  • viOpen will not verify the presence of the instrument. If the device is not present or not turned on, you will not discover this until you attempt to communicate with the instrument. viOpen will take less time to execute if address-check is off.