FieldServer FS-8704-06 - Manual (Page 21)

FS-8704-06 BACnet IP Driver Manual Page 21 of 57
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Appendix A.4.1. Accessing Priority Array information
The Priority Array table and its “In_Use” (or Not Relinquished) state are stored internally to every Map Descriptor, and cannot be accessed directly. The information can
be accessed indirectly by specifying the following Data Arrays which will maintain an exact copy of the Priority Array Table for the Map Descriptor.
Section Title
Map_Descriptors
Column Title
Function Legal Values
DA_Pri_Array
Name of Data Array where the Priority Array Table will be stored. Location 0 is the Relinquish Default value and
locations 1 to 16 the different entries of the Priority Array Table. Up to 16 alphanumeric
characters
DA_Pri_Array_Offset* Starting location in Data Array. 1-65535 , 0
DA_Pri_In_Use
Name of Data Array that indicates if a particular Priority Value is in use. Location 0 indicates whether the Relinquish
Default has been set and locations 1 to 16 indicate whether the index is in use (1), or Relinquished (0). Up to 16 alphanumeric
characters
DA_Pri_In_Use_Offset* Starting location in Data Array. 1-65535, 0
// Analog Output Map_Descriptor for testing Priority Arrays
Map_Descriptors
Map_Descriptor_Name , Object_Type , Object_Instance , Function , Data_Array_Name , Data_Array_Offset , Node_Name , Length , Relinquish_Default , DA_Pri_Array , DA_Pri_Array_Offset , DA_Pri_In_Use , DA_Pri_In_Use_Offset
CMD_AOP_1 , AO , 1 , Passive , DA_OUT , 0 , N1 11 , 1 , 40.56 , DA_Pri_Array_1 , 0 , DA_Pri_in_use_1 , 0
Appendix A.5. Relinquishing Control of a Point as a Client
It is possible relinquish control of a point by writing a null to the correct priority level. The following example illustrates how this is done.
Map_Descriptors
Map_Descriptor_Name , Data_Type , Function , Scan_Interval , Data_Array_Name , Data_Array_Index , Node_Name , Address , Length , Write_Priority , Service
CMD AO
, AO , Rdbc , 1.0s , DA AO , 2 , N1 1 , 1 , 1 , 7 , -
CMD AO Rel , AO , Wrbx , 1.0s , DA AO , 3 , N1 1 , 1 , 1 , 7 , Relinquish
Map Descriptor CMD AO is a Read
Map Descriptor that will write at
priority 7 if a write-through occurs
Map Descriptor CMD AO Rel is a Write-on-Change
Map Descriptor that will write a NULL at priority 7
(i.e. release Priority Array entry 7) when written to.
Note that the length must be 1.