FixPt Data Type Propagation
Configure the data type and scaling of the propagated signal based on information from the reference signals.
Description
The FixPt Data Type Propagation block allows you to control the data type and scaling of signals in your model. You can use this block in conjunction with fixed-point blocks that have their Specify data type and scaling parameter configured to Inherit via back propagation.
The block has three inputs: Ref1 and Ref2 are the reference inputs, while the Prop input back propagates the data type and scaling information gathered from the reference inputs. This information is then passed on to other fixed-point blocks.
The block provides many choices for propagating data type and scaling information. For example, you can use:
- The number of bits from the Ref1 reference signal, or use the number of bits from widest reference signal.
- The range from the Ref2 reference signal, or use the range of the reference signal with the greatest range.
- A bias of zero, regardless of the biases used by the reference signals.
- The precision of the reference signal with the least precision.
You specify how data type information is propagated with the Propagated data type parameter list. If the parameter list is configured as Specify via dialog, then you manually specify the data type via the Propagated data type edit field. If the parameter list is configured as Inherit via propagation rule, then you must use the parameters described in Inheriting Data Type Information.
You specify how scaling information is propagated with the Propagated scaling parameter list. If the parameter list is configured as Specify via dialog, then you manually specify the scaling via the Propagated scaling edit field. If the parameter list is configured as Inherit via propagation rule, then you must use the parameters described in Inheriting Scaling Information.
Precedence Rules
The precedence of the dialog box parameters decreases from top to bottom. Additionally:
- Double-precision reference inputs have precedence over all other data types.
- Single-precision reference inputs have precedence over integer and fixed-point data types.
- Multiplicative adjustments are carried out before additive adjustments.
- The number of bits is determined before the precision or positive range is inherited from the reference inputs.
Dialog Box Parameters
- Propagated data type - Use the parameter list to propagate the data type via the dialog box, or inherit the data type from the reference signals. Use the edit field to specify the data type via the dialog box.
- Propagated scaling - Use the parameter list to propagate the scaling via the dialog box, or inherit the scaling from the reference signals. Use the edit field to specify the scaling via the dialog box.
- Override data type(s) with doubles - If checked, the data type is overridden with doubles.
Characteristics
| Characteristic | Description |
|---|---|
| Input Port | Any data type supported by the blockset |
| Direct Feedthrough | Yes |
| Sample Time | Inherited |
| Scalar Expansion | Yes |
| States | 0 |