PIACC - Access modes

Enumarators overview

• PI_Read (1) - Read access
  
• PI_Update (2) - Update access
  
• PI_Write (3) - Write access
  
• PI_undefined (0) - Access mode undefined
  

Enumerator details

1. PI_undefined - Access mode undefined
   Code: 0
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2. PI_Read - Read access
   

   The database or property will be provided for read access. Any write or update access will be denied.

   Code: 1
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3. PI_Update - Update access
   

   Update access provides data for a property handle without locking, i.e. concurrency control is partially disabled. Concurrent updates will be detected and an error 0067 will be written to the error log file in case of concurrency conflict. The first attempt for storing the instance will succeed, further attempts are denied.

   In case of concurrency conflicts the instance can be reread ( reset() ) and the update can be repeated.

   For databases the update mode has the same effect as write mode.

   Code: 2
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4. PI_Write - Write access
   

   The database or property handle is opened in write access. For property handles, concurrency control will be enabled (pessimistic locking), i.e. when selecting an instance for Write access ( get() , position() ) the instance is locked (write lock) until the instance is unselected. The instance can be read via other property handles, but will be provided in read mode, only.

   Code: 3
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