filepath is an optional path to a CAN database file from which to import the channel (signal) configurations.

If filepath is unwired (empty), the channel configuration is obtained from MAX. The MAX CAN channels are in the MAX CAN Channels listing within Data Neighborhood.

channel list is the array of channel names to initialize and start as a task. Each channel name is provided in an array entry.

You can type in the channel list entries as string constants, or you can obtain the list from MAX or another CAN database by using CAN Get Names.vi. Channel names are case sensitive.

You can initialize the same channel list with different interface, mode, or sample rate, because each task reference is unique.

The following paragraphs describe the syntax of each channel name. Brackets indicate optional fields.

[message.]channel

• message refers to the message in which the channel is contained. The message name must be followed by a decimal point.

  If the channel name occurs in multiple messages, you must specify the message name to identify the channel uniquely. Within MAX, channels with the same name in multiple messages are shown with a yellow exclamation point.

  If the channel name is unique across all channels, the message name is not required.

• channel refers to the channel (signal) name in MAX or the CAN database (indicated by filepath).

The following examples demonstrate the channel list syntax:

1. List of channels, each channel name unique across all messages.

   myChan1

   myChan2

   myChan3

   If you are using mode dependent channels, and each channel name is not unique, you will need to use a special syntax described in the Mode Dependent Channel Syntax section at the end of the function description.

2. List of channels, with one channel duplicated across two messages. MyChan2 and MyChan3 must be unique across all messages.

   myMessage1.myChan1

   myChan2

   myMessage2.myChan1

   myChan3

interface specifies the CAN interface to use for this task.

The interface input uses a ring typedef in which value 0 selects CAN0, value 1 selects CAN1, and so on.

The default (unwired) value is MAX default, which means to use the default interface as defined in the Message/Channel configuration properties. If the default interface in MAX is All, or if filepath is wired to use a CAN database (not MAX), the interface is a required input to this VI.

The Channel API and Frame API cannot use the same CAN network interface simultaneously. If the CAN network interface is already initialized in the Frame API, this function returns an error.

The special interface values 256 and 257 refer to virtual interfaces. For more information on usage of virtual interfaces, refer to Frame to Channel Conversion.

mode specifies the I/O mode for the task. For an overview of the I/O modes, including figures, refer to the Channel API Basic Programming Model.

Input

Input channel data from received CAN messages. Use CAN Read.vi to obtain input samples as single-point, array, or waveform.

Use this input mode to read waveforms of timed samples, such as for comparison with NI-DAQ waveforms. You also can use this input mode to read a single point from the most recent message, such as for control or simulation.

For this mode, the channels in channel list can be contained in multiple messages.

Output

Output channel data to CAN messages for transmit. Use CAN Write.vi to write output samples as single-point, array, or waveform. Each sample value that you write is transmitted in a message on the network. If you write an array or waveform, the samples are buffered for subsequent transmit.

For this mode, there are restrictions on using channels in channel list that are contained in multiple messages. Refer to CAN Write.vi for more information.

Output Recent

Output channel data to CAN messages for transmit. This mode is used with sample rate greater than zero (periodic transmit). Use CAN Write.vi to provide a single sample per channel. Each periodic message uses the sample values from the most recent CAN Write.vi.

For this mode, there are restrictions on using channels in channel list that are contained in multiple messages. Refer to CAN Write.vi for more information.

Timestamped Input

Input channel data from received CAN messages. Use CAN Read.vi to obtain input samples as an array of sample/timestamp pairs (Poly VI types ending in Timestamped Dbl).

Use this input mode to read samples with timestamps that indicate when each message is received from the network.

For this mode, the channels in channel list must be contained in a single message.

sample rate specifies the timing to use for samples of the task. The sample rate is specified in Hertz (samples per second). A sample rate of zero means to sample immediately.

For mode of Input, a sample rate of zero means that CAN Read returns a single point from the most recent message received, and greater than zero means that CAN Read returns samples timed at the specified rate.

For mode of Output, a sample rate of zero means that CAN messages transmit immediately when CAN Write is called, and greater than zero means that CAN messages are transmitted periodically at the specified rate.

For mode of Output Recent, sample rate must be greater than zero (periodic transmit).

For mode of Timestamped Input, sample rate is ignored.

When the interface specifies a virtual interface (256 or 257), and mode is Output or Output Recent, this sample rate must be zero (greater than zero not supported).