FieldServer Metasys N2 FS-8700-19 User Manual
Page 11
FS-8700-19_Metasys_N2 Driver Manual
Page 11 of 51
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Point Type
Conditions that will trigger a COS report
AI
point status change (e.g. override)
change in alarm or warning status
NB: no value changes within the normal band are reported by COS!
AO
point status change (e.g. override)
NB: no value changes within the normal band are reported by COS!
BI, BO
point status change (e.g. override); includes current value (On/Off)
ADI, ADF, BD none; COS cannot be used with internal data types.
Using Override and Release – N2Open
It is not normally necessary to use the Override command explicitly as the
FieldServer automatically uses this command when the Current Value attribute of a
point is written. For any other attribute it uses the Write command. It will sometimes
be necessary to send a Release command to an overridden point, however. To do
this, a Map Descriptor must be configured with Function set to wrbx and
MN2_Function set to Release. Then, when any value is stored to the Map
Descriptor data location, the Release command will be sent to the N2Open point
specified by the Map Descriptor.
4.4.2.2.
VMA Map Descriptor Parameters
Column Title
Function
Legal Values
Node_Name
Name of Node to fetch
data from
One of the node names
specified in “Client Node
Descriptor” above
Data_Type
Data type
AI, AO, DI, DO, Driver
(used for ADF, ADI and
BD)
Length
Length of Map Descriptor
1
Address
Starting address of read
block
1-256
MN2_Type
Data type specifier to be
set when Data_Type has
been set to Driver
5-7
ADI, ADF and BD types: using the “Driver” Data_Type and MN2_Type fields
The VMA protocol uses a byte value to specify the data types. The standard types
AI, AO, DI and DO correspond to a byte value of 1 through 4 respectively. The types
ADF, ADI and BD are believed to correspond to a byte value of 5 through 7
respectively. If the user wishes to use any other type value based on knowledge of a
particular VMA configuration, then that value may also be specified here. Refer to
Section 4.4.5 for a specific example.