On large networked systems with many clients, you can improve communications turn-around time by using memory caching.
When caching is enabled, data that is read from an I/O Device is stored temporarily in the memory of the I/O Server. If another request is made (from the same or another client) for the same data within the cache time, the CitectSCADA I/O Server returns the value in its memory, rather than rereading the I/O Device. Data caching results in faster overall response when the same data is necessary by many clients.
A cache time of 300 milliseconds is recommended. Avoid using long cache times (in excess of 1000 milliseconds), as this may negatively impact the timely delivery of information to the system.
Note: Do not use data caching for disk I/O devices as they implement a cache themselves.