Information on Using SICL and VISA in the Same Application

Agilent Technologies' implementation of VISA uses SICL internally to do instrument I/O.  While Agilent Technologies does not officially support the use of both SICL and VISA in a  single application, you may be able to use SICL and VISA together successfully if you avoid certain problem areas listed below:

• Do not use both VISA and SICL to talk to the same device:
  • If VISA and SICL are used to talk to the same device, VISA can lose track of the state of the device and communications errors may occur.
• Do not mix SICL ilock() and VISA viLock() calls on the same device and do not ilock() an interface used by VISA:
  • If a user calls VISA's viLock() to lock a device, that device can still be accessed via SICL sessions.
  • If a user calls SICL's ilock() and then VISA's viLock() on the same device, the viLock() call will succeed, but subsequent VISA calls to that device may return a VI_ERROR_SYSTEM_ERROR.
• Do not intermix iwaithdlr() and viEnableEvent() calls:
  • Calling iwaithdlr() in one thread and viEnableEvent() in another can cause loss of interrupts. This is because the viEnableEvent() code needs to have SICL interrupts disabled for a critical_section of code.  iwaithdlr() will re-enable them and potentially cause a lost interrupts.
  • Note also, that the SICL iwaithdlr() call will terminate when a VISA interrupt occurs.
• Do not close the last VISA resource manager session until all open SICL sessions have been closed. (This is only a problem on Windows 95 / 98.)
  • VISA, when closing the last Default Resource Manager session, will call _siclcleanup() which closes all open SICL sessions, whether or not they were opened via VISA or directly from SICL. Any open SICL sessions will be invalid after the _siclcleanup() call.

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