RS232 I/O Support (xPC Target)

xPC Target

RS-232 Setup Block

The Block Parameters dialog box for the RS-232 Setup block contains the following fields.

Parameter
Description

Port

From the list, select COM1, COM2, COM3, or COM4. This is the serial connection the target PC uses to communicate with the RS-232 device.

Baudrate

From the list, select 115200, 57600, 38400, 19200, 9600, 4800, 2400, 1200, 300, or 110.

Number of Databits

From the list, select either 7 or 8.

Number of Stopbits

From the list, select 1 or 2.

Parity
From the list, select None, Odd, or Even.

Protocol

From the list, select None or XOnXOff. If your serial device does not support hardware handshaking, or your application software requires XOn/XOff handshaking, you might need to select XOn/XOff

Send Buffer Size

Enter the size, in bytes, of the send buffer.

Receive Buffer Size

Enter the size, in bytes, of the receive buffer.

The Send Buffer Size and Receive Buffer Size must be large enough to hold the data to be sent or received during each model step. It is important to be aware that the buffers must be large enough to also store old data from a prior model step in the event that the entire data transmission was not completed during the prior step.

Initialization Structure

Enter the name of the structure containing the initialization messages and the expected acknowledgements when the model is initialized. If you are not using initialization messages, enter an empty matrix in this box.
For information on creating this structure, see Creating RS-232 Message Structures (Synchronous) and Creating RS-232 Message Structures (Asynchronous)

Termination Structure

Enter the name of the structure containing the termination messages and expected acknowledgements when the model is terminated. If you are not using termination messages, enter an empty matrix in this box.

Parameter	Description
Port	From the list, select `COM1`, `COM2`, `COM3`, or `COM4`. This is the serial connection the target PC uses to communicate with the RS-232 device.
Baudrate	From the list, select `115200`, `57600`, `38400`, `19200`, `9600`, `4800`, `2400`, `1200`, `300`, or `110`.
Number of Databits	From the list, select either `7` or `8`.
Number of Stopbits	From the list, select `1` or `2`.
Parity	From the list, select `None`, `Odd`, or `Even`.
Protocol	From the list, select `None` or `XOnXOff`. If your serial device does not support hardware handshaking, or your application software requires XOn/XOff handshaking, you might need to select XOn/XOff
Send Buffer Size	Enter the size, in bytes, of the send buffer.
Receive Buffer Size	Enter the size, in bytes, of the receive buffer. The Send Buffer Size and Receive Buffer Size must be large enough to hold the data to be sent or received during each model step. It is important to be aware that the buffers must be large enough to also store old data from a prior model step in the event that the entire data transmission was not completed during the prior step.
Initialization Structure	Enter the name of the structure containing the initialization messages and the expected acknowledgements when the model is initialized. If you are not using initialization messages, enter an empty matrix in this box. For information on creating this structure, see Creating RS-232 Message Structures (Synchronous) and Creating RS-232 Message Structures (Asynchronous)
Termination Structure	Enter the name of the structure containing the termination messages and expected acknowledgements when the model is terminated. If you are not using termination messages, enter an empty matrix in this box.

The RS232 Setup block defines the number of databits, baudrate, protocol, and so on, for each COM port used in your Simulink model. Each model that uses RS232 I/O must have one RS232 Setup block for each COM port in the model. The RS232 Setup block does not have any inputs or outputs.

If your host PC and target PC are connected using serial communication, one COM port on your target PC is dedicated for communication with your host PC. You cannot use this COM port in your block diagram as an I/O device. For example, if the target PC uses COM1 for the communication with the host PC, COM1 cannot be used by your block diagram. An error message displays if you use COM1 as an I/O device in your block diagram. The error message appears when you attempt to build and download the target application. In this example, it would be necessary for you to use COM2 as an I/O device in your block diagram. If you are using TCP/IP as your host PC to target PC communications protocol, then you can use any COM ports with RS232 I/O drivers in your block diagram.

Note COM1 and COM3 share interrupt line 4. Similarly, COM2 and COM4 share interrupt line 3. To provide maximum performance, the COM port interrupt line on your target PC used for serial communication is disabled while real-time tasks that include RS232 blocks are executing. This also means that when COM1 is disabled, COM3 is also disabled since they both share the same interrupt line. For this case, you would use either COM2 or COM4 as your RS232 I/O device.

RS-232 Simulink Block Reference RS-232 Send/Receive Block (Synchronous)