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ASCII Decode

Parse ASCII character vector into Simulink values

  • Library:
  • Simulink Real-Time / RS232

  • ASCII Decode block


The ASCII Decode block parses an input character vector according to a format specifier similar to scanf and makes converted values available to the real-time application.



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The input vector can be either 8-bit or 16-bit and signed or unsigned. If the data format is 16-bit, the block ignores the upper 8 bits of each entry.

Data Types: int8 | uint8 | int16 | uint16


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Output ports corresponding to items in Format string.


Number of variables determines the number of output ports.

Data Types: double | int8 | uint8 | int16 | uint16 | int32 | uint32


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Enter a scanf like format string. Each format specifier such as %d must match a corresponding part of the input vector. Literal strings in the format must match the first character plus the number of characters. The format specifiers follow the normal description for scanf.

An example format string is:

'alpha %d bravo %f\n'

Programmatic Use

Block Parameter: format

Enter the number of output ports for this block. For example:

If Format string has the value of %xmore text%x and the input vector for the block has cdmabcdefgh90, you must specify the value of the Number of variables parameter as 2.

The first variable is assigned the value 0xcd. Next, the character vector mabcdefgh is considered a match to more text because:

  • The first character for both character vectors is m.

  • Both character vectors have the same number of characters.

The second variable is then assigned the value 0x90. The character vector mabcdefgh does not have to match exactly the value of Format string. This behavior is different from the behavior for scanf, which requires an exact match.

Programmatic Use

Block Parameter: nvars

A cell vector with the same number of elements as specified in Number of variables can specify a different data type for each output port. A single element is replicated. For example:


{ } — The three outputs are doubles.

{'uint8'} — The three outputs are uint8.

{'uint16', 'double', 'uint8'} — The first output is a uint16, the second output is a double, and the third output is a uint8.

Programmatic Use

Block Parameter: varids
Introduced in R2020b