CANbus

If your model controller includes a CANbus port, you can implement the following methods of data exchange:

PLC to PLC

PLC to Remote Device

Access a PLC via PC

Getting Started with CANbus

CANbus ID numbers range from 1 to 63. The ID number is contained in SI 8. You can assign an ID number by:

Entering a value into SI 8 via Information Mode.
Storing a value into SI 8 as shown below, either by storing a constant number or by linking a register value.

Linking a register value allows you to enable an end-user to enter an Unit ID number via the HMI panel. You can create a Display for this purpose as shown below.

Note ♦	The default ID # is 1.
♦	UniCAN ID # range is from 1-60.

You must initialize the CANbus ports of all controllers in the network to the desired CANbus mode, by using a COM Port Init FB as shown below.

Note ♦	The baud rates of all controllers in the network must be set to the same rate. Baud rate is limited by cable length, as described in the CANbus Specifications section below.
♦	The COM Init FB used to initialize the CANbus port should be included in the Main Routine of the Ladder application.

Power Requirements: 24VDC ( ±4%), 40mA max. per unit
Galvanic Isolation between CANbus and controller: Yes
Baud rate	Max. Network Cable Length:
1 Mbit/s	25 m
500 Kbit/s	100 m
250 Kbit/s	250 m
125 Kbit/s	500 m
100 Kbit/s	500 m
50 Kbit/s	1000 m
20 Kbit/s	1000 m
Note ♦	Cable lengths over 500 meters require an additional power supply.
Wiring Considerations
Use twisted-pair cable. DeviceNet® thick shielded twisted pair cable is recommended.
Network terminators: These are supplied with the controller. Place terminators at each end of the CANbus network. Resistance must be set to 1%, 121Ω, 1/4W.
Connect the ground signal to the earth at only one point, near the power supply.
The network power supply need not be at the end of the network.
Maximum number of controllers in a network: 63.

About CANbus System Operands

The function of some operands depends on whether the CANbus network is defined as CANbus ISC, CANopen or UniCAN. The operand function changes according to the type selected in the COM Init function

To learn how to use these operands to communicate data, check the topic CANbus ISC, via Network Operands.
#	Description	Turns ON when:	Turns OFF when:	Reset by:
SB 236	CANbus Network communication error		Error is fixed.
SB 237	CANbus Network disabled

When using CANbus ISC

When using UniCAN

SB#	Description	Turns ON when:	Turns OFF when:	Reset by:
SB 240	CANopen: Configuration downloaded	The CANopen Configuration FB is downloaded to the PLC	No CANopen Configuration is present	PLC
SB 241	CANopen: Configured	CANopen Configuration was successful	CANopen Configuration failed	PLC
SB 242	CANopen: SDO in Progress	SDO is busy transferring data	SDO is not in progress	PLC
SB 243	CANopen: SDO transfer failed	SDO data transfer fails	SDO transfer begins	PLC

When using CANopen

When using CANbus ISC

When using UniCAN

Description

Value

Comments

SDW 7

UniCAN, CANbus ISC Error

If not 0, contact technical support

CANopen: Number of failed Send attempts

Number of times that data send failed

SDW 8

CANopen: Number of failed Sync attempts

Number of times that send SYNC failed

SDW 56

UniCAN Send message counter

Is initialized when CANbus Port Init runs, then increments at every UniCAN Send.

Note that only messages sent from a UniCAN Send are counted

CANopen: PDO Send Counter

Byte structure:

PDO4 | PDO3 | PDO2 | PDO1

SDW 57

UniCAN Receive message counter

Is initialized when CANbus Port Init runs, then increments at every UniCAN Receive.

Note that only messages received from a UniCAN Send are counted, not Broadcast messages or Check if Alive responses.

CANopen: NMT/SDO Send Counter

High bits: NMT

Low bits: SDO

SDW 29

CANopen: Bus is OFF Counter

Number of times bus was OFF

SDW 33

CANopen: SDO Number of Bytes

SDO upload: number of bytes received

SDO download: number of bytes sent

SDW 34

CANopen: Abort Code in SDO Abort

Value	Message
0503 0000h	Toggle bit not alternated
0504 0000h	SDO protocol timed out
0504 0001h	Client/server command specifier not valid or unknown
0504 0002h	Invalid block size (block mode only)
0504 0003h	Invalid sequence number (block mode only)
0504 0004h	CRC error (block mode only)
0504 0005h	Out of memory
0601 0000h	Unsupported access to an object
0601 0001h	Attempt to read a write only object
0601 0002h	Attempt to write a read only object
0602 0000h	Object does not exist in the object dictionary
0604 0041h	Object cannot be mapped to the PDO
0604 0042h	The number and length of the objects to be mapped would exceed PDO length
0604 0043h	General parameter incompatibility reason
0604 0047h	General internal incompatibility in the device
0606 0000h	Access failed due to a hardware error
0607 0010h	Data type does not match, length of service parameter does not match
0607 0012h	Data type does not match, length of service parameter too high
0607 0013h	Data type does not match, length of service parameter too low
0609 0011h	Sub-index does not exist
0609 0030h	Invalid value for parameter (upload only)
0609 0031h	Value of parameter written too high (upload only)
0609 0032h	Value of parameter written too low (upload only)
0609 0036h	Maximum value is less than minimum value
060A 0023h	Resource not available: SDO connection
0800 0000h	General error
0800 0020h	Data cannot be transferred or stored to the application
0800 0021h	Data cannot be transferred or stored to the application because of local control
0800 0022h	Data cannot be transferred or stored to the application because of the present device state
0800 0023h	Object dictionary dynamic generation fails or no object dictionary is present (e.g. object dictionary is generated from file and generation fails because of a file error)
0800 0024h	No data available

SDW 36

CANopen: Bus OFF error

Value	Message
0	No error
1	Stuff Error: More than 5 equal bits in a sequence have occurred in a part of a received message where this is not allowed
2	Form Error: Wrong format in fixed format part of a received frame
3	AckError: The message this CAN controller transmitted was not acknowledged by another node
4	Bit1Error: During the transmission of a message (with the exception of the arbitration field), the device wanted to send a recessive level (“1”), but the monitored bus value was dominant
5	During busoff recovery this is set each time a sequence of 11 recessive bits is monitored. This enables the CPU to monitor the proceeding of the busoff recovery sequence (indicates that the bus is not stuck at dominant or continuously disturbed
6	CRCError: The received CRC check sum is incorrect
7	Unused code: may be written by the CPU to check for updates

The CANopen System Operand addressing scheme changed as of VisiLogic version 7.00, OS 2.00 (Standard Division) OS 5.02 (Enhanced Division).

You can choose to continue editing older applications using previous VisiLogic versions contained in the VisiLogic Version Swapper. Note that in this case the controller must use an older OS.

However, if you choose to update the application and OS, note that you must change the system operands according to the following table.

System Integers		System Double Words
Old	New	24	7
200	211	25	8
201	212	26	56
202	213	28	57
203	214
204	215
205	216
206	217
207	218
208	219
240	220
241	221
242	222
243	223
244	224
245	225

CANbus Compilation Errors

At compilation or download, VisiLogic may display this error: "Illegal CAN Communication Driver specification - see help"

To learn how to use these operands to communicate data, check the topic CANbus ISC, via Network Operands.
#	Description	Turns ON when:	Turns OFF when:	Reset by:
SB 200	CANbus Network operand
SB 201	CANbus Network operand
SB 202	CANbus Network operand
SB 203	CANbus Network operand
SB 204	CANbus Network operand
SB 205	CANbus Network operand
SB 206	CANbus Network operand
SB 207	CANbus Network operand
SB 208	CANbus Network operand
SB 209	CANbus Network operand
SB 210	CANbus Network operand
SB 211	CANbus Network operand
SB 212	CANbus Network operand
SB 213	CANbus Network operand
SB 214	CANbus Network operand
SB 215	CANbus Network operand
SB 237	CANbus Network disabled

SB#	Description	Turned ON	Turned Off	Comments
200	Broadcast bit	When UniCAN broadcast MB is received whose status is ON.	By user	The user must initialize this SB
201	High Priority Send Buffer Status	When full	When not full
202	Low Priority Send Buffer Status	When full	When not full