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5.3.5. Map Descriptor Example – Strategy 2. This example differs from the previous example, in that it divides the memory being emulated into chunks to avoid having a large sparse array.
When a poll is received, the driver looks through the Map Descriptors and f inds one with a matching node and one whose address and length
cover the poll’s address.
Map_Descriptor_Name ,Data_Array_Name ,Data_Array_Offset ,Function ,Node_Name ,Address ,Length
Chiller1_emulation1 ,DA_CHILLER1 ,0 ,Passive ,Chiller1 ,1024 ,256
Chiller1_emulation2 ,DA_CHILLER1 ,256 ,Passive ,Chiller1 ,2048 ,256
The same Data
Array is used for
both Map
Descriptors.
By using the same
Data Array and
changing the
offset the data can
all be packed into
a smaller array.
1024 = 0x400
2048 = 0x800
These two address ranges cover
almost all the data fields in a 200
series chiller.
A few more Map Descriptors could be
added to serve the remaining data
field addresses.