How to Configure Multiple Update Rates for a Device when using AVEVA (formerly Wonderware) Suitelink/DDE

As far as I can see, it's only possible to specify one global update interval for Suitelink Clients connected to the system. I need to read data from one PLC at different Update Intervals using the Suitelink Protocol. I know you can do this via OPC as each client connection specifies the update interval that it requires by OPC group. This is not possible with Suitelink.
Do you have any way to specify multiple update rates for the same channel/device in TOP Server for SuiteLink or DDE clients? The example that I am using is that I need to get Boolean values into InTouch at a 1 second interval, but Analog values only at a 5 second interval. All via Suitelink. How do I do this?

The Scan Rate for the individual static tag is also used with SuiteLink connections (only when static tags are configured, though). To assign a specific scan rate with dynamic tag references, you can append the following syntax to the end of the address:

@xxxx

where xxxx is the desired scan rate in milliseconds.

For instance, to request Modbus holding register 400001 at a scan rate of 5,000 milliseconds, you would use the dynamic address of 400001@5000. This syntax can be used in conjunction with data type modifiers, as well.

For instance, to request Modbus holding register 400001 as a floating point at a rate of 10,000 milliseconds, you would use the dynamic address of 400001@10000,float.

Only OPC connections ignore the individual tag scan rates on static tags because the client is responsible for setting this per OPC standards.

To define scan rates at a topic level, though, TOP Server also has an Alias Map that allows you to define multiple alias topics per channel/device/group in your project. Each alias also includes a setting for Scan Rate Override. This would be equivalent to the group scan rates you're familiar with in OPC connections.

These scan rates for the Alias topic names override the individual tag rates unless you set the Topic rate to 0 (leaves the default at 1000 ms).  By setting them to different values you get different scan rates for different topics. You can create new topics/Aliases pointing to the same Channel and Device, so you can have two topics polling the same PLC at different rates. You just need to make sure to use the appropriate alias topic in your SuiteLink or DDE client based on the update/scan rate you desire for the associated items.

For our blog post covering how to use the TOP Server Alias Map, click here.

You can download the latest version of TOP Server here.