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FS-8700-49_Data_Aire_DAP Page 11 of 48
FieldServer Technologies 1991 Tarob Court Milpitas, California 95035 USA Web:www.FieldServer.com
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4.4.4. Map Descriptor Example 1 - Everything
The FieldServer listens passively for all possible data from the device called ‘unit1’ and stores the data in an array called ‘DA_01’.
The data that is obtained from ‘unit1’ is dependent on the type of device. Irrespective of the device type the arrangement of data,
stored in DA_01, is fixed. If a data field cannot be obtained from ‘unit1’ then the array is left with a zero value for that data field.
// Client Side Map Descriptors
Map Descriptors
Map_Descriptor_Name, Data_Array_Name, Data_Array_Offset, Function, Node_Name, Address, Length, DA_Func, Scan_Interval
Read_Node_01, DA_01, 0, RDBC, Unit1, 0, 1300, Everything, 2.5s
4.4.5. Map Descriptor: Example 2 – Writing a Set-Point.
// Client Side Map Descriptors
Map Descriptors
Map_Descriptor_Name, Data_Array_Name, Data_Array_Offset, Function, Node_Name, Address Length, DA_Field, Scan_Interval
Write_SP_01, DA_SETPOINTS, 0, WRBC, Unit1, 0, 1, nom_h_setpt, 120s
It is recommended
that the format of
the Data Array be
FLOAT as the data
read from the unit
consists of bits,
bytes and real
numbers.
The node name
connects the Map
Descriptor to a node
definition which in
turn is connected to
a port.
Always set the Address
to zero and the length to
1300 as this is the max
number of data points
that can be read
Tells the
driver that
this Map
Descriptor is
used to (poll
&) store a
complete
data set from
the unit.
The scan interval is used to
control the minimum time
between poll messages. It
may take several polls /
messages to obtain a
complete data set (the
number is dependent on the
unit type.)
The setpoint is
obtained from
this Data Array.
Always leave the
address set to zero
and the length as
one
.
Select the data field from Appendix B.3.
Ensure that the keyword can be written to the
unit type identified as unit1.
Example. If unit1 is a Chiller then the above
Map Descriptor will not function correctly as it
can only be used to write to unit types
7,9,14,15.
This is how often the data will be written to
the device. Reduce the scan interval when
using a dart. The dart will only take control
of the devices when the network has been
idle for at least 50 seconds. If polls are
generated too often, the dart will never
exercise control.