Required and visible parameters
To pass specific data into an Add-On Instruction, make the parameter required. A required parameter must pass as argument for a call to the instruction. The instruction verifies the argument. In ladder diagram, specify an argument tag for these parameters. If a required parameter does not have an associated argument, the routine containing the call to the Add-On Instruction does not verify.
For Output parameters, make a parameter visible if you do not need to pass the parameter value to an argument, but want to display the value of the parameter for troubleshooting.
Required parameters are always visible. InOut parameters are always required and visible. You can access any Input and Output parameter as a member of the tag of the instruction, regardless of whether the parameter is required or visible.
Required and visible parameters in Ladder Logic
Required and Visible parameter settings affect the display of an instruction:
Parameter Type | Required | Visible | Ladder Diagram value displays |
|---|---|---|---|
Input | Y | Y | Y |
Input | N | Y | Y |
Input | N | N | N |
Output | Y | Y | Y |
Output | N | Y | Y |
Output | N | N | N |
InOut | Y | Y | N |
If you have a parameter for which the user must specify a tag as its source for input or its destination as output, make the parameter required. Any required parameters are automatically visible.
All InOut parameters are required and visible by default.
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