9.5. Special Cases
9.5.1. Multiple clients on the same Windows computer
It is possible to send data from the data server to more than 1 client on the same Windows computer. For example, it may be necessary to send the same process data to a spreadsheet application and a Graphical User Interface application, both running on the same Windows computer. This is represented by Example 1 below.
You may also want to send data from different data server applications to seperate clients on the same Windows computer. This is represented by Example 2 below.
The Example 1 connection can be accomplished using:
1 copy of the Connect Server on the data server.
1 copy of the Cascade DataHub on the data server (recommended).
1 copy of Cascade Connect on the Windows computer.
It would require one Cascade Connect license and one Cascade DataHub license.
The Example 2 connection can be accomplished using:
1 copy of the Connect Server on each data server.
1 copy of the Cascade DataHub on each data server (recommended).
2 copies of Cascade Connect on the Windows computer.
It would require two Cascade Connect licenses and one Cascade DataHub license.
9.5.2. Single Windows client using multiple Cascade Connects
It is also possible for some Windows clients to send and receive data with more than one copy of Cascade Connect. This allows the Windows client to communicate with multiple data sources. This configuration is currently being used to implement a 'hot standby' strategy by at least one of our customers, using InTouch as the Windows client application. You can read more about this type of connection in our Implementing Hot Standby using InTouch white paper.
The above connection can be accomplished using:
1 copy of the Connect Server on each data server.
1 copy of the Cascade DataHub on each data server (recommended).
2 copies of Cascade Connect on the Windows computer.
It would require two Cascade Connect licenses and two Cascade DataHub licenses.
9.5.3. Windows client in read-only mode
Unidirectional, read-only mode means that data is transferred from the data server to Windows, but not vice versa. This option is useful for situations where data needs to be viewed, but shouldn't be changed. For example, operators may be allowed to change variables to control a process at their workstation, while the management view-station is secured as read-only so that process changes are not made in isolation.
Your choice between this mode or bidirectional (read/write) mode can influence how difficult it will be to set up some of the usage scenarios given in this chapter. For a summary of these scenarios with respect to read-only vs. read-write mode, please see the table in the When to use the Cascade DataHub section of the Technical Information chapter of this manual.
You can implement read-only mode by selecting Read Only Mode in the Program Launch Options section of the Cascade Connect Setup window.