Cache and forward buffering is one of those topics that can challenge users of HMI software. One way we are using this this blog is to demystify product topics that appear complicated but aren't. Cache and forward buffering is a powerful feature of Interact Xpress (InteractX) HMI Visualization Software that is under utilized because people think it's complicated. It's not.
Cache and forward buffering is an efficient low cost method of increasing the reliability of and availability of your database logged data in InteractX. It is especially useful for applications in regulated industries where "the dog ate my homework" isn't an acceptable excuse to inspectors looking for data that wasn't logged due to a network failure or server downtime.
Cache and forward buffering performs 3 simple functions automatically by enabling a simple check box in InteractX:
1. It monitors the connection to a remote database and identifies any loss of communication.
2. If any disconnection is identified it stores all log data locally on the InteractX stations hard drive. (Cache)
3. When the database connection is re-established it copies all of the locally logged data back to the remote database. (Forward)
This process provides a level of data security that is only topped by redundant technologies at a considerably higher cost. This feature is appreciated in industries such as pharmaceutical, food and beverage, heat treating, and even military contractors. Essentially anyone who logs data that they don't want to lose to a Server shutdown, cable failure, network switch failure or other infrastructure problem. Isn't that everyone who logs data?
Enabling cache and forward buffering in InteractX is extremely simple:
a. Cache Exists is a binary property that will toggle true when InteractX is caching data rather than sending it to a remote database. This should be attached to a tag and displayed on an indicator to signal the operator that InteractX has lost its connection with the remote database.
b. Clear Cache is a binary input that will attempt to forward the cache data to the remote database. This should be assigned to a tag that is attached to a momentary push button. This will allow the operator to attempt to clear the local cache after re-connecting to the local database.
We hope you have some applications for cache and forward buffering, that this is of value, and with the help of this post, you can easily implement this feature. One thing to keep in mind is that there is no need or benefit to turning this feature on for a local database. We'd recommend against enabling caching when the database is stored on the same PC as InteractX.
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Andy Balderson, Division Marketing Manager, Parker Hannifin - Electromechanical Division North America
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