FieldServer FS-8700-80 - Manual (Page 19)

McQuay Micro Tech Open Protocol Driver Manual Page 19 of 43
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6.3.4 Map Descriptor Example 1 – Read Everything.
In this example the Map Descriptor tells the driver to read all data fields known for the Node. The data fields are read sequentially and the values placed in the
Data Array at a location determined by the driver. Appendix C.3 outlines the data read and the Data Array location of each field. There is no way of telling this
command to read some fields more often than others. Each field is read in turn and when the end of the list is reached the driver starts at the beginning again.
Map_Descriptor_Name , Data_Array_Name , Data_Array_Offset , Function , Node_Name , Length , Scan_Interval , Field_Name , Device_Scaling
Read Chiller 1
, DA_CHILLER1 , 0 , Rdbc , Chiller1 , 1 , 1.0s , Everything , Yes
6.3.5 Map Descriptor Example 2 – Read a particular Data Field.
This example illustrates how to read data for one particular field of interest. The data is read every 2.0 seconds and the value obtained is stored in the Data
Array named DA_OPERATIONAL_MODES at location 10.
Map_Descriptor_Name , Data_Array_Name , Data_Array_Offset , Function , Scan_Interval , Node_Name , Length , Field_Name
Chiller10_Op_Mode , DA_OPERATIONAL_MODES , 10 , Rdbc , 0s , Chiller10 , 1 , Chiller Operation Mode
Many validation or
error messages report
the name of the Map
Descriptor in the
message and, thus it is
strongly recommended
that unique names be
used. Each field read has its
value stored in this
Data Array. The
location is dependent
on the field name. The
length of the Data
Array should be at least
200, so that all
parameters can be
stored.
The driver will read
every data field
known for the
device. The values will be scaled
before storage.
Example: The ‘Evaporator
Refrigerant Pressure’ will be
stored by dividing the raw
value read by 10.
This parameter
connects the Map
Descriptor to a
Node which in turn
connects the Map
Descriptor to a port.
Ensure that the field name is spaced and spelled exactly as it is
printed in Appendix C.3