readPoint
readPoint — gets the
value of a Cascade DataHub point.
Syntax
For C++:
ST_STATUS readPoint( | CDataHubPoint& | point, |
| | bool | create=TRUE, |
| | bool | force=TRUE); |
ST_STATUS readPoint( | LPCTSTR | pointname, |
| | bool | create=TRUE, |
| | bool | force=TRUE); |
For Java:
Exception readPoint(DataHubPoint point);
Exception readPoint( | DataHubPoint | point, |
| | boolean | create, |
| | boolean | force); |
Exception readPoint(String pointname);
Exception readPoint( | String | pointname, |
| | boolean | create, |
| | boolean | force); |
For C#:
Exception readPoint(DataHubPoint point);
Exception readPoint( | DataHubPoint | point, |
| | bool | create, |
| | bool | force); |
Exception readPoint(String pointname);
Exception readPoint( | String | pointname, |
| | bool | create, |
| | bool | force); |
Parameters
- point
- A
DataHubPoint object. The name
member must be valid.
- pointname
- The name of the point.
- create
- If
TRUE, then the point is created if it does
not already exist. If FALSE and the point
does not exist, then an error message will be
generated.
- force
- If
a valid connection to the DataHub exists but the message is
undeliverable immediately (due to the TCP buffer being full),
then if the force parameter is TRUE, the message is queued and
will be transmitted when possible.
Returns
For C++:
- ST_OK if the command was
successfully sent to the DataHub.
- ST_NO_TASK if a connection to
the DataHub does not exist.
- ST_ERROR if the connection
socket is unable to send the message.
Description
This method requests that the
value of the specified point be transmitted. The point value is
received as a point message, which causes the virtual method onPointChange
to be called. The point value cannot be obtained
synchronously.
If the create
parameter is FALSE and the point does not
exist, then the DataHub will respond with an error, and onError will be called with the
following arguments:
| status: ST_NO_POINT |
| msg: "Point does not exist" |
Examples
readPointValue(_T("strPoint1"));CDataHubPoint point;
point.name = "strPoint1";
readPoint(&point, FALSE);
