Legacy Serial Port

Send and receive data over mainboard baseboard serial port

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Libraries:
Simulink Real-Time / RS232 / Mainboard

Description

The Send/Receive block sets up the serial interface to send and receive basic character streams. This block has basic First In, First Out (FIFO) Read blocks inside the subsystem. It generates output as an array of packed integers (settable at 8 bits, 16 bits, or 32 bits). Characters appear in the lower byte and received status information appears in the upper byte.

For more information, see RS-232 Serial Communication and RS-232 Legacy Drivers.

Ports

Input

XMT — Vector of data to transmit

vector

Vector of the data used to transmit over the port.

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

Output

RCV — Vector of data received over serial port

vector

Vector containing data that has been received from serial port.

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

Parameters

Serial port type — Port type that is being accessed

Legacy Serial Port (default) | USB Serial Port | Specify

Specify the serial port type for communications. Choose Legacy Serial Port or USB Serial Port to specify the type of port used. Or, choose Specify to manually specify the path of the port used. For more information about serial ports, see RS-232 Serial Communication.

Dependencies

Setting Serial port type to Legacy Serial Port or USB Serial Port displays the Serial port number parameter in which you can specify the port number.

Setting Serial port type to Specify displays the Serial port parameter in which you can specify the port path.

Programmatic Use

Block Parameter: portType

Serial port number — Port number that is being accessed

1 (default) | positive integer

Specify the serial port number for communications.

If using USB-to-serial adapters, the target computer detects these adapters as ttySUSB0, ttySUSB1, and so on in the order that the adapters are connected to the serial devices.

The order of port assignment is retained through the power cycle of the target computer or serial device if there is no change in the connections to the ports.

Dependencies

This parameter is visible if Serial port type is set to Legacy Serial Port or USB Serial Port.

Programmatic Use

Block Parameter: portNum

Serial port — Serial port device path that is being accessed

/dev/ttyS0 (default) | node path

Specify the serial port device path for communications. The path can be the device path of a Legacy Serial Port or USB Serial Port.

Dependencies

This parameter is visible if Serial port type is set to Specify.

Programmatic Use

Block Parameter: nodePath

Baud rate — Baud for transferring data

115200 (default) | 57600 | 38400 | 19200 | 9600 | 4800 | 2400 | 1200 | 600 | 300 | 110

Select a baud for transmitting and receiving data through the modem.

Programmatic Use

Block Parameter: baud

Number of data bits — Number of bits per character

8 (default) | 7 | 6 | 5

Select the number of bits that encode a character.

Programmatic Use

Block Parameter: width

Number of stop bits — Number of stop bits for port

1 (default) | 2

Select the number of stop bits for the character stream.

Programmatic Use

Block Parameter: nstop

Parity — Parity for checking data transfer

None (default) | Even | Odd | Mark | Space

Select a parity for checking data integrity.

Programmatic Use

Block Parameter: parity

Enable auto RTS/CTS — Enable RTS/CTS handshake

off (default) | on

To enable the Request To Send/Clear To Send (RTS/CTS) handshake of the Universal Asynchronous Receiver-Transmitter (UART) for flow control, select this check box. Serial controllers use the RTS/CTS handshake to prevent data loss due to hardware FIFO overflow on the device that you are sending to.

Usually, the interrupt service routine executes quickly enough to empty the FIFO. If your model gets FIFO overruns, select this check box.

Programmatic Use

Block Parameter: ctsmode

Max Output count — Maximum number of elements for block to return

1024 (default) | integer

Enter the maximum number of elements that you want returned by a single call to this block. The block uses this parameter to set the output vector width.

If you select the Read to delimiter check box and if the block does not find the delimiter before it reads Receive maximum read characters, the output vector is empty.

Programmatic Use

Block Parameter: maxread

Min Output count — Minimum number of elements for block to return

1 (default) | integer

Enter the minimum number of characters to read. If the FIFO does not contain at least this number of characters, the output vector is empty.

Programmatic Use

Block Parameter: minread

Read to delimiter — Return characters including message delimiter

on (default) | off

For the block to return all characters in the FIFO, up to and including the specified delimiter, select this check box.

If the buffer has errors, such as framing errors, the modem returns characters regardless of the presence of the delimiter. These returned characters help diagnose errors such as mismatched baud rates.

If the block does not find the delimiter before it reads Receive maximum read characters, the output vector is empty.

Programmatic Use

Block Parameter: usedelimiter

Delimiter — Numeric value of message delimiter

13 (default) | integer

Enter the numeric value of the character that is the message delimiter. Any value from 0 to 255 is valid. The common case looks for 10 (line feed) or 13 (carriage return).

Programmatic Use

Block Parameter: delimiter

Receive data type — Data type of receiver

8 bit int null terminated (default) | 8 bit uint null terminated | count+16 bit int | count+16 bit uint | count+32 bit int | count+32 bit uint

This parameter specifies the data type of the receiver. The 8-bit data types produce a NULL-terminated character vector in the output vector.

For 16-bit and 32-bit data types, the first element contains the number of valid elements in the rest of the output vector.

For 8-bit data types, only the character data is in the output vector, and a NULL terminator is appended. The 16-bit or 32-bit wide data types cause the error status from the UART to be placed in the second byte of each data element. (The error status contains the parity, overrun, framing, and break bits.) The character data is in the bottom 8 bits of each element. The first element of the vector contains the number of data elements that follow.

Programmatic Use

Block Parameter: odtype

Receive FIFO size — FIFO size in bytes

1024 (default)

This parameter specifies the receive FIFO size in bytes.

Example: 1024

Programmatic Use

Block Parameter: fifosize

Data Types: int32

Transmit Data Type — Data type of transmitter

count+32 bit int (default) | count+32 bit uint | count+16 bit int | count+16 bit uint | 8 bit int null terminated | 8 bit uint null terminated

This parameter specifies the data type of the transmitter. The 8-bit data types require a NULL-terminated character vector in the input vector.

The 16-bit and 32-bit data types reserve the first full element to contain the number of elements to expect in the rest of the input vector. Only the low-order byte of each data element is sent. Setting this data type enables a wider data type to hold the bytes.

If the data stream requires a NULL byte, select one of the 16-bit or 32-bit data types. Because the 8-bit data types are NULL-terminated character vectors, the NULL byte terminates the character vector.

Programmatic Use

Block Parameter: idtype

Sample Time — Sample time

0.01 (default) | numeric

Enter the base sample time or a multiple of the base sample time. -1 means that sample time is inherited.

Programmatic Use

Block Parameter: sampletime

Version History

Introduced in R2008a

R2021b: USB to Serial for RS232 Blocks

The RS232 mainboard blocks support connecting USB serial adapter ports. The Serial port parameter of the Legacy Serial Read block, Legacy Serial Write block, Legacy Serial Setup block, Legacy Serial Port block, and Legacy Serial Port F block means that you can select a USB Serial Port or a Legacy Serial Port.