Host Serial Receive

Configure host-side serial communications interface to receive data from serial port

  • Library:
  • Motor Control Blockset / Protection and Diagnostics

Description

The Host Serial Receive block specifies the configuration of the data that it receives from the target hardware.

The data package that the block receives is limited to 16 bytes of ASCII characters, including package headers and terminators. Calculate the size of a package by including the package header, or terminator, or both, and the data size. This table shows the number of bytes in each data type.

Data TypeByte Count

single

4 bytes

int8 and uint8

1 byte

int16 and uint16

2 bytes

int32 and uint32

4 bytes

For example, if your data package has a package header 'S' (1 byte) and package terminator 'E' (1 byte), that leaves 14 bytes for the actual data. If your data is of type int8, there is space in the data package for 14 int8s. If your data is of type uint16, there is space in the data package for 7 uint16s. If your data is of type int32, there is space in the data package for only 3 int32s, with 2 bytes left over. Even though you could fit two int8s or one uint16 in the remaining space, you should not, because you cannot mix data types in the same package.

The number of data types that can fit into a data package determine the data size. In the preceding example, the data size is 14 for int8 and 7 for uint16. When the data size exceeds 16 bytes, unexpected behavior, including run-time errors, are likely to occur.

Ports

Output

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A first in, first out (FIFO) buffer receives the data. At every time step, the data port outputs the requested values from the buffer.

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

The status of the transaction. The status can be one of the following values:

  • 0 — No errors

  • 1 — A timeout occurred when the block was waiting to receive data

  • 2 — There is an error in the received data (checksum error)

  • 3 — SCI parity error flag — Occurs when a character is received with a mismatch

  • 4 — SCI framing error flag — Occurs when an expected stop bit is not found

Dependencies

To enable this port, select the Output receiving status parameter.

Data Types: uint16

Parameters

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Specify a serial port to receive communication from the target hardware. Select an available serial port from the list. You can configure the selected port using the Host Serial Setup block. If you do not configure a serial port, the block prompts you to do so. Each Host Serial Receive block must have a configured serial port. If you use multiple ports in your simulation, you must configure each port separately.

Specifies the data located at the front of the received data package, which is not part of the data being received, and generally indicates start of data. The additional package header must be an ASCII value. You can use a text value or a numeric value in the range (0–255). You must put single quotes around the text that you enter in this field, but the quotes are not received and they are not included in the total byte count.

Specifies the data located at the end of the received data package, which is not part of the data being received, and generally indicates end of data. The additional package terminator must be an ASCII value. You can use a text value or a numeric value in the range (0–255). You must put single quotes around text entered in this field, but the quotes are not received and they are not included in the total byte count.

Specifies the data type of the block output.

Specifies the output data size or the number of values that should be read at every simulation time step.

Specifies the initial or default output value of the block. This value is used, for example, if a connection timeout occurs and the Action taken when connection times out parameter is set to Output the last received value, but the block has not received any value yet.

Specifies what to output if a connection timeout occurs.

  • Output the last received value — The block outputs the value received at the preceding time step. If the block did not receive a value previously, it outputs the value of the Initial output parameter.

  • Output custom value — The block outputs a user-defined value. Use the Output value when connection times out parameter to define this custom value.

  • Error — The block outputs an error.

Specifies a custom value that the block outputs when a connection timeout occurs.

Dependencies

To enable this parameter, set Action taken when connection times out to either Output custom value or Error.

Determines how often the Host Serial Receive block is called (in seconds). When you set this value to -1, the model inherits the sample time of the model. To execute this block asynchronously, set Sample time to -1.

Select this parameter to enable the status output port that provides the status of the transaction. If you clear this parameter, the block hides the status port.

Select this parameter to block the simulation while receiving data. Clear this parameter if you do not want the read operation to block the simulation.

If you enable the blocking mode, the model blocks the simulation while it is waiting to receive the requested data. When you do not enable the blocking mode, the simulation runs continuously.

Introduced in R2020a