CANbus Network Problems

Compiler error 43

This error may result because:

The project includes both CANbus modes. Note that a controller cannot run UniCan and CANbus ISC simultaneously.
The Ladder application does not include a COM Init FB that initializes the CANbus port.

SB 236 indicates that there is an error in the CANbus network.

SI 236 CANbus Network: Failed Unit ID. Note that the first 3 bits turn ON only when the controller is unable to broadcast via the CANbus port. The value of SI 236 indicates the following messages:

Value	Message	May result from:
0	No Acknowledgement	CANbus power failure, crossed wires, incorrectly set termination points.
1	CANbus OFF
2	CANbus Warning error	Poor transmission quality due to faulty wiring, or if the cable length exceeds recommendations.
4	One or more networked units cannot be read. If this bit is ON, check SI 238, SI 240-243.

SI 237 CANbus Network Communication Error Code is a bitmap which indicates the LAST unit that cannot be read. Note that each controller can receive messages from up to 8 others. Example: Assume that there are 6 controllers in the network (3,6,8,13,17,34). Controller 3 is waiting for data from controllers 8 and 13 and 17. If the controller does not receive data from controller 13 (assume a 1 second timeout) then SI 237 will contain a value of 13. Bit 4 in SI 236 will also turn ON. Once controller 3 has received the data, Bit 4 turns OFF.

SIs 240, 241, 242, and 243 serve as a bitmap indicating which unit is in error. If, for example, the network includes unit ID numbers 8, 9 and 13, and PLC #9 cannot be accessed, then the ninth bit in SI 240 will turn ON. When the error is fixed, the bit falls to OFF.

CANbus troubleshooting

Problem	Possible cause	Recommended Action
Failed communication	Baud rate settings	All controllers in the network must be set to the same CANbus baud rate. Baud rate may be set: By initializing a port via the COM Init FB. Temporarily via Info mode;however, note that the baud rate will be reset at the next power-up
	Termination resistors	Termination resistor settings are provided in the chapter Communications in the controller's user guide.
	CANbus power supply	Check that the CANbus power supply is properly connected, and that the voltage is in the permissible range as described in the chapter Communications in the controller's user guide.
	Incorrect ID number	You may not have assigned the correct unit ID number in your operand addresses (between 1-63). Check the OPLC settings tab Communicate with OPLC.
PC cannot communicate with bridge	Incorrect setting	When you communicate with the controller unit that you are using as a bridge to the network, either enter the ID# of the bridge or select Direct Connection in the OPLC settings tab Communicate with OPLC.
PC cannot communicate with network	Communication settings	Make sure the current RS232 parameters in your project are the same as the parameters that are actually in the bridge. Check these topics:Check Network Status,Vision Communication PC Settings
	Incorrect baud rate	The bridge's RS232 port's baud rate cannot be set below 9600.