I2C Express VI

Download PDF

Requires: myRIO Toolkit or roboRIO Toolkit

Writes data to or reads data from an Inter-Integrated Circuit (I2C) slave device through the I2C channels on the myRIO or the roboRIO.

The roboRIO uses a 3.3 V voltage rail on the I2C port for powering I2C peripherals and provides 3.3 V DIO lines for generating I2C signals.

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 I2C channel to which to write data to or read data from the I2C slave device.
Connections	Shows the myRIO or the roboRIO pins that correspond to the data line (SDA) and clock line (SCL).
Mode	Specifies the mode of operation that this Express VI uses to communicate with the I2C slave device. Mode contains the following options: Write—Specifies that this Express VI writes data to the I2C slave device. Read—Specifies that this Express VI reads data from the I2C slave device. Write/Read—Specifies that this Express VI writes data to the I2C slave device and then reads a specified number of bytes from the I2C slave device.
Speed	Specifies the transfer rate of the I2C channel. The default is Standard mode (100 kbps).
View Code	Displays the underlying code of this Express VI.
Connection Diagram	Shows the I/O connector pinouts on the myRIO or the roboRIO. The highlighted pinouts represent the channels that you configure.

Parameter	Description
Slave Address (7-bit)	Specifies the address of the I2C slave device which this Express VI reads data from or writes data to. You must specify the address in 7 bits. Some I2C devices might have an 8-bit address in which the first 7 bits represent the address and the last bit represents the mode of operation. For this kind of I2C devices, you must specify Slave Address (7-bit) using the seven most significant bits.
Bytes to Write	Specifies the data bytes to write to the I2C slave device. This input is available when you set Mode to Write or Write/Read.
Byte Count	Specifies the number of bytes to write to the I2C slave device. This input is available when you set Mode to Read or Write/Read.
error in (no error)	Describes error conditions that occur before this node runs.

Parameter	Description
Bytes Read	Returns the data bytes that this Express VI reads from the I2C slave device. This output is available when you set Mode to Read or Write/Read.
error out	Contains error information. This output provides standard error out functionality.