dOPC Client Toolkit Help file
TdOPCGroup Class
dOPC.TdOPCGroup
C++
public: class TdOPCGroup : public TCollectionItem;
C#
public class TdOPCGroup : TCollectionItem;
Visual Basic
Public Class TdOPCGroup
Inherits TCollectionItem

dOPC

class for an OPC Group 

TdOPCGroup provides collections of items from OPC DA servers.

OPC Clients can use this groups to organize, read and write values of this items. For example the group might represent items in a particular operator display or report. The items can be read or values can be written to them. Exception-based connections can also be created between the client and the items in the group and can be enabled and disabled as required. A client can configure the rate at which a server should provide changes of the values of the items.

TdOPCGroup Events 
Description 
TdOPCGroup Methods 
Description 
AsyncRead performs an asynchronous read of the value, quality and timestamp information for all items either in the group or, if it is not nil, in the parameter aItemList. 
AsyncWrite performs an asynchronous write of the value, quality and timestamp information for all items either in the group or, if it is not nil, in the parameter aItemList. 
CancelLastAsyncCall requests that the server cancels the last outstanding AsyncRead or AsyncWrite transaction. 
fills EUInfo and EUType for all items in this group
GetEUInfos fills the properties EUInfo and EUType for all items either in the group or, if it is not nil, in the parameter aItemList. 
GetState fills the parameter GroupState with the current state of the group. 
Refresh generates an event for all active items in the group (whether they have changed or not) to refresh their values. 
RefreshMaxAge generates an event for all active items in the group that have not changed their values for the duration of the passed MSecs (milliseconds) to renew their values. 
SyncRead performs a synchronous read of the value, quality and timestamp information for all items either in the group or, if it is not nil, in the parameter aItemList. 
SyncWrite performs a synchronous write of the value, quality and timestamp information for all items either in the group or, if it is not nil, in the parameter aItemList. 
TdOPCGroup Properties 
Description 
DeadBand contains the change of percent of an item value that will cause an exception report of this value to the client. 
DefaultItem contains the TdDefaultItem for the group. 
IGroup contains the interface to access to the functions that OPC DA Servers contain to manage groups. 
IsActive contains the current Active state of the group. 
IsPublic contains the current Public state of the group. 
IsSubscribed contains the current Subscribed state of the group. 
LocaleId contains the current LCID for the group. 
Name 
Name contains the current name of the group. 
OPCItems contains a TdOPCItems object which contains TdOPCItem objects that belong to the group. 
Parent contains a reference to the parent TdOPCServer object. 
SignalEvent is always triggered (PulseEvent) if one item of the group changes. This is important for thread issues only. 
Tag 
Tag has no predefined meaning. 
TimeBias (minutes) contains the TimeZone bias of the group. 
UpdateRate (milliseconds) contains the current rate at which the items of the group are updated. 
XMLHoldtime (milliseconds) instructs the server to hold off returning from refreshing calls until the specified time is reached. 
XMLWaittime (milliseconds) instructs the server to wait the specified time after the XMLHoldtime is reached before returning. 
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