UART Express VI
- Updated2023-02-21
- 3 minute(s) read
Requires: myRIO Toolkit, roboRIO Toolkit, or NI ELVIS RIO Control Toolkit
Writes data to or reads data from a Universal Asynchronous Receiver/Transmitter (UART) device through the UART channels.
With the roboRIO, you also can use this VI to write data to or read data from an RS-232 device through the RS-232 channel.
| Dialog Box Options |
| Block Diagram Inputs |
| Block Diagram Outputs |
Dialog Box Options
| Parameter | Description |
|---|---|
| Node name | Specifies the name of this Express VI. You can also double-click the name of this Express VI on the expandable node to edit the name. |
| Channel | Specifies the UART channel to write data to or read data from the UART device. With the roboRIO, you also can specify the RS-232 channel to write data to or read data from the RS-232 device. |
| Connections | Shows the pins that correspond to the receive input line and the transmit output line. |
| Mode | Specifies the mode of operation for communicating with the UART device. Mode contains the following options:
|
| Communication settings | Specifies the configuration for communicating with the UART device. With the roboRIO, you also can specify the configuration for communicating with the RS-232 device. Communication settings contains the following options:
|
| View Code | Displays the underlying code of this Express VI. |
| Connection Diagram | Shows the I/O connector pinouts. The highlighted pinouts represent the channels that you configure. |
Block Diagram Inputs
| Parameter | Description |
|---|---|
| Characters to Write | Specifies the characters to write to the UART device. With the roboRIO, you also can specify the characters to write to the RS-232 device. This input is available only when you set Mode to Write. |
| Character Count | Specifies the number of characters to read from the UART device. With the roboRIO, you also can specify the number of characters to read from the RS-232 device. This input is available only when you set Mode to Read. |
| error in (no error) | Describes error conditions that occur before this node runs. |
Block Diagram Outputs
| Parameter | Description |
|---|---|
| Character Count | Returns the number of characters that this Express VI reads from the UART device. With the roboRIO, this output also returns the number of characters that this Express VI reads from the RS-232 device. This output is available when you set Mode to Write. |
| Characters Read | Returns the characters that this Express VI reads from the UART device. With the roboRIO, this output also returns the characters that this Express VI reads from the RS-232 device. This output is available when you set Mode to Read. |
| error out | Contains error information. This output provides standard error out functionality. |
UART Details
The UART lines on the MXP ports are electrically identical to DIO lines on the MXP port. The UART signals are transistor-transistor logic (TTL) compatible and have the following characteristics:
- Logic low—0 V to 0.8 V
- Logic high—2 V to 5 V
The RS-232 lines on the roboRIO are compliant with TIA/EIA-232-F voltage levels. The following are the valid voltage levels:
- Logic one—-5 V to -15 V
- Logic zero—+5 V to +15 V
Related Information
I/O Connectors (myRIO Toolkit)
I/O Connectors (roboRIO Toolkit)