CANbus, Layer 2

Vision controllers support data communication with remote devices such as frequency converters according to the CANbus V2.0 standard.

A Vision can both send and receive standard messages with 11-bit identifiers, as well as extended messages with 29-bit identifiers.

Using CANbus Layer 2

At power-up:

Assign each networked controller a unique Unit ID number.
Initialize the CANbus port to CANbus Layer2 via a COM Init function.
Activate the configuration.

Send

The Send function determines the data that is sent to a specified remote device.

Parameter Name	Purpose
Send Port	Select one of the four available ports.
Identifier	Select either the 11-bit (default), or the extended 29-bit identifier.
CANbus ID of Target Device	Enter the number of the target device either by: -Directly entering it - Select the address of the MI containing the ID number.
Number of Bytes to Send	A CANbus message can contain up to 8 data bytes.
Data to Send: Start Address	Enter the start address of the vector containing the data.

Scan

The Scan function enables a PLC to receive data from a specified remote device and write it to a vector of registers.

Parameter Name	Purpose
Receive Port	Select one of the four available ports.
Identifier	Select either the 11-bit (default), or the extended 29-bit identifier.
CANbus ID of Sending Device	Enter the number of the target device either by: -Directly entering it - Select the address of the MI containing the ID number.
Number of Bytes to Receive	A CANbus message can contain up to 8 data bytes.
Store Received Data: Start Address	Enter the start address of the vector to contain the data.
Data Arrived	Turns ON when the message is received. Note ♦ This MB must be reset by the user.

Scan_EX

This function enables the controller to receive any messages that arrive via CANbus.

In order to run Scan_Ex, you must initialize the port to Scan_Ex.

Note that Scan_EX is active, you cannot access the PLC via network bridge. If your application requires communication via bridge, you must re-initialize the port using another COM Init function as shown below.

Parameter Name	Purpose
RX Frame bits	After the message is received: -if the status of the bit operand =0 the received message contains an 11-bit identifier, -if the status of the bit operand =1 the received message contains a 29-bit identifier,
RX Identifier	This operand contains the received message identifier. Note that if the identifier is 29-bit, you must use a DW.
RX Number of bytes	This operand contains the number of bytes to be received in the message. A CANbus message can contain up to 8 data bytes.
Rx Data Vector	Enter the start address of the vector to contain the data.
Message Arrived	Turns ON when the message is received. Note ♦ Must be reset by the user.

Note ♦	Enhanced Vision only: note that you can run both CANbus Layer 2 and CANopen if you select the relevant Com Port option in the COM Init function.
♦	Note that you can initialize the port to Scan or to Scan_Ex. -Scan: PLC can receive messages from a specific device via a specific port. You can configure up to 4 ports, and receive up to 4 messages per scan -Scan_Ex: PLC can receive messages from any device, and not via a specified port. Only one message may be received per scan.
♦	Prevent CANbus network overload by using a Send condition to activate functions. Do not place them directly on the left Ladder rail.