Dynamic Allocation of External Memory Buffers

In previous versions, the XMP external memory was statically allocated at firmware compile time.

In version 20010119 and later, specific buffers of the XMP external memory are dynamically allocated. The dynamic allocation feature allows an application to efficiently use the XMP controller's on-board memory and allows for future expansion. The dynamically allocated buffers currently include the Frame Buffer and Record Buffer. Each of these buffers sizes are recalculated during a call to mpiControlConfigSet(...) if there is a change in any of the associated ControlConfig values.

The Frame Buffer is used for motion on each axis. The Frame Buffer is directly associated with the number of EnabledAxes in the MPIControlConfig structure. The Frame Buffer will be allocated to the minimum size required to support the number of enabled axes. The default number of EnabledAxes is eight (8).

The Record Buffer is used for the on-board data recorder. The Record Buffer is directly associated with the number of EnabledRecord in the MPIControlConfig structure. The Record Buffer will be allocated to the minimum size required to support the number of enabled records. The default number of EnabledRecords is 3064. Each record is the size of one memory word.

The meiControlExtMemAvail(...) method has been added to discover how much memory is available on your controller.

The meiControlExtMemAvail(...) method will return the number of memory words available. Since each record size is one memory word, the size returned from the above function can be used to increase the Record Buffer to maximum size possible. This greatly improves client/server operation of Motion Scope and any application used for data collection.

WARNING! Due to the nature of dynamic allocation and the clearing of external memory buffers mpiControlConfigSet(...) should ONLY be called at motion application initialization time and NOT during motion.

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