Back to FBD referenceTypical FBD symbol for IN
Inputs, outputs, and values
IN
Program input
The IN block represents a program input signal. It has no input ports and emits the current input image value on Q.
Typical FBD symbol
IN
Q
Inputs
| Name | Type | Required | Description |
|---|---|---|---|
| This block has no input ports. | |||
Outputs
| Name | Type | Required | Description |
|---|---|---|---|
| Q | BOOL | Yes | The boolean input value passed into the diagram. |
Stateful
No, the block does not keep internal state.
Internal state allows a block to account for previous input values, elapsed time, or an accumulated result.
Behavior rule
Reads the input image value at the scan boundary and passes it to Q.
Practical use
- start pushbutton;
- part-present sensor;
- safety door signal.
What to watch
- Expecting IN to store state by itself. The value comes from the program input image.