PACiS GTW GTW/EN T/C40, Technical Manual

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Communication GTW/EN CT/C40
PACiS Gateway Page 49/64
7. OPC PROTOCOL
7.1 Implementation
All required OPC Interfaces are supported for both OPC 1.0 and OPC 2.0 Data Access
Standards as well as the Browse Interface (
OPC DA 2.05 ).
The OPC Protocol basically operates as a data librarian. The controlling application creates
Process Tags by passing a name and value to the DLL. The DLL records the data point and
makes it available to any OPC Client application by name. The controlling application may
change the value of the data at any time, and all attached clients would be automatically
notified. Callback notification is provided for any Process Tag that is modified by an OPC
Client connection. (The application has control over which tags are OPC_WRITEABLE only
for control datapoints.)
Registration
The Opc Server registration is made by the gateway installation sofware if you choiced OPC
Protocol.
Two arguments are needed for this phase: CLSID and PROGID
CLSID: {8087E613-3ED9-11D7-827E-00E029555839}
PROGID: Schneider Electric.OPC SERVER.V2.0
Initialization
When this phase is executed, the DLL performs all necessary initialization of COM/DCOM
and creates the OPCServer Interface object to be used for client connections. The specified
ServerRate defines how fast the OPC Client data connections are refreshed (ServerRate is
configured in registry)
Creating Process Tags
As each process tag is created, the DLL returns a HANDLE to identify the point for future
references, (updates), from the application. The naming convention used for browsing
operations, (OPC_NS_FLAT or OPC_NS_HIERARCHIAL), is a function of how the names
are assigned by the controlling application. If segmented names are used to create the tags,
(strings containing the delimiter ‘.’), the DLL will automatically configure the name space as
hierarchial, otherwise a flat name space is used. The names are configured by PACiS SCE.
Each process tag is configured with a type which identifiy the type of Variant used for
update.
Type of datapoint Type of TAG configurable Type of VARIANT used
SPS (single point status) BOOL,BYTE VT_BOOL,VT_UI1
DPS (double point status) BOOL,BYTE VT_BOOL,VT_UI1
MPS (multiple point status) BYTE,WORD VT_UI1,VT_UI2
MV (measurement) FLOAT VT_R4
TPI (Tap changer indicator) WORD VT_I2
Counter DWORD VT_I4
SPC (single point control) BOOL,BYTE VT_BOOL,VT_UI1
DPC (double point control) BOOL,BYTE VT_BOOL,VT_UI1
Setpoint FLOAT VT_R4
Only SPC,DPC and Setpoint are OPC_WRITABLE tags.