Back to FBD referenceTypical FBD symbol for CONST
Inputs, outputs, and values
CONST
Constant BOOL value
The CONST block has no inputs. Its Q output equals the VALUE parameter on every scan.
Typical FBD symbol
CONST
Q
Inputs
| Name | Type | Required | Description |
|---|---|---|---|
| This block has no input ports. | |||
Outputs
| Name | Type | Required | Description |
|---|---|---|---|
| Q | BOOL | Yes | The constant boolean value. |
Parameters
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
| VALUE | boolean | Yes | false | The value emitted on Q. |
Stateful
No, the block does not keep internal state.
Behavior rule
Always emits the configured TRUE or FALSE value.
Practical use
- diagram testing;
- forcing a logic branch on or off;
- learning examples.
What to watch
- Leaving CONST TRUE in a real diagram after temporary testing.