What happens?
Sporadically, the controller sends no sync telegram via the CAN bus for one task cycle. For this task cycle, there is no sync-based CAN process data communication with the CAN devices connected to the controller.
When does this behaviour occur?
The above-described behaviour may occur if the CAN sync interval time selected in the Com. cycle period field (CAN parameters tab of the CAN master in the PLC configuration) is set to the same value as or a multiple of the interval time of the task responsible for the CAN update. The task responsible for the update is defined in the Update task field in the Module parameters tab of the CAN master.
Which products are affected?
PLC Designer from V3.0
Short-term measures:
Compare the CAN sync interval time selected in the Com. cycle period field with the interval time of the task responsible for the CAN update (see the property Interval in the task in the Task configuration).
If the CAN sync interval time is identical with or a multiple of the task interval time, select a value smaller than the task interval time or a multiple of it in the Com. cycle period field.
Example:
Task interval time = 50ms
=> possible values for the CAN sync interval time = 46ms, 96ms, 146ms,...
Evaluation/recommendations:
Sporadically, the controller sends no sync telegram for one task cycle. For this task cycle, no process data is exchanged between the controller and the devices connected via the CAN bus. In the case of drive controllers, this may lead to jumps in the motion process.
