| xPC Target | |
The Pack Block is used to convert one or more Simulink signals of varying data types to a single vector of uint8 as required by the Send Block. The data types for the different signals must be specified as part of the block parameters while the sizes of each signal are determined automatically.
As seen in the figure above, the data types of each of the signals have to be specified as a cell array of strings in the correct order. Once this is done, the block will automatically convert itself to one with the correct number of input ports. There is always one output port. The supported data types are: double, single, int8, uint8, int16, uint16, int32, uint32, and boolean. The byte alignment field specifies how the data types are aligned. The possible values are: 1, 2, 4 and 8. The byte alignment scheme is simple, and ensures that each element in the list of signals starts on a boundary specified by the alignment relative to the start of the vector. For example, say the Input port data types are specified as
and an alignment of 4 is used. Assume also that all the signals are scalars. The first signal will then start at byte 0 (this is always true), the second at byte 4, the third at byte 8, the fourth at byte 12, and the fifth at byte 16. Note that the sizes of the data types used in this example are 1, 4, 4, 2, and 8 bytes respectively. This implies that there are "holes" of 3 bytes between the first and second signal and 2 bytes between the fourth and fifth signal.
A byte alignment of 1 means the tightest possible packing. That is, there are no holes for any combination of signals and data types.
| Note Individual elements of vector/matrix signals are not byte aligned: only the entire vector/matrix is byte aligned. The individual elements are tightly packed with respect to the first element. |
| | UDP Send Block | UDP Unpack Block | |
