The Check Variable Status action checks
the status, or availability to access, a device
variable.
This can be used to determine if a device and it variables
is available (meaning the device is in a Started state)
before continuing with a series of actions or before
execution portions of the application logic (before
executing triggers).
In the normal flow of a trigger's logic, an action would reference a device variable and would have the failure route defined accordingly if the action failed. There are cases where a decision about the ability to access a device is made at a higher level before continuing with the application logic.
Input tab
The Input tab allows you to specify the device variable whose status needs to be checked. For this example D[100].
| Parameter | Description |
|---|---|
| Input Variable | The device variable to check for ability to access. |
Output tab
| Parameter | Description |
|---|---|
| Status | The output status of the device variable. If the variable was successfully accessed, the status will be zero. If there was an error accessing the Input Variable, the status will have an error code that was returned from the device driver. |
Routing tab
| Parameter | Description |
|---|---|
| Good Value | The route to take when the variable was accessed successfully. |
| Bad Value | The route to take when the device driver had an error accessing the variable. |