Dynamic Point Count

Citect SCADA counts I/O device addresses dynamically at runtime.

The client process keeps track of the dynamic point count. This includes variable tags used by the following:

• Alarms
• Trends
• Reports
• Events
• OPC DA Server
• EWS Server
• Pages and Super Genies
• Cicode functions (TagRead, TagWrite, TagSubscribe, TagGetProperty and TagResolve)
• Any tag referenced by Cicode
• Reads or writes using DDE, ODBC, CTAPI or external OPC DA clients.

A particular variable tag is only counted towards your point count the first time it is requested. Even if you have configured a certain tag on a particular page in your project, the variable tag will not be counted towards your point count unless you navigate to that page and request the data.

You should also be aware of the following:

• A dynamic point count is tag based, not address based. For example, two tags that use the same PLC address will be counted twice.
• For the multi-process mode, each server component will accumulate its own point count which will add to the total of the client dynamic point count.

If two trend tags use the same variable tag, it will be counted once. If two server components use the same tag(s) (say alarm and trend), the tags will not be counted twice when the point count gets totaled in the client process.

• For the multi-process mode, the client component will also accumulate its own point count, which will include all the variable tags that are used by the process.
• For the multi-process mode, the machine point count will be the point count of the client component, or the point count added up from each server component, depending on whichever is bigger. If the server point count is greater than 500, the client component point count is disregarded.
• Reading properties of a tag with TagGetProperty() or TagSubscribe() will cause that tag to be included in the point count, even if the value is not read.
• Persisted I/O (memory devices), local variables and disk I/O variable tags will not count towards the dynamic point count, unless they are written to by an external source (via OPC, DDE, ODBC, or CTAPI). For example, if you use an OPC client to write to a local variable, each local variable will be counted once the first time it is used.

Note:
• You can use the CitectInfo() Cicode function or the General page in the Citect SCADA Kernel to determine the point count status of a client process.
• You can specify the point count required by a client computer by using the [Client]PointCountRequired INI parameter.

See Also

Published June 2018