Bidirectional Bindings

Tag bindings and Query bindings can be set up as bidirectional bindings. This means that not only is the binding assigning the tag value or query value into the property, but it is also listening for changes to that property, which will then be written back to the tag or the database.

Tag Bindings

Tag bindings can be made bidirectional simply by checking the checkbox. The "Fallback Delay" is the amount of time that the value will remain at the written value, waiting for a tag change to come in. If no tag change comes in within the allotted time (specified in seconds), then the property will fall-back to the value as it was before the write. This is needed, because sometimes even if a write succeeds, another write or ladder logic in a PLC might have written something different, even the old value, in which case no tag change event will be generated. As a rule of thumb, the fallback delay should be twice the tag's scan class rate.

Query Bindings

When a query binding is made bidirectional, it needs an UPDATE query to execute when the property changes. You can use the special marker {this} as a placeholder for the new value.

Bidirectional query bindings are only available on scalar-typed properties (i.e. not Datasets)