McQuay Micro Tech Open Protocol Driver Manual | Page 16 of 35 |
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 finds 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 |
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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.
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