Omron C200HW-CORT21-V1, Operation Manual

Page: 43 / 144

Performance
Section 2-3
26
Note
When the Unit is configured to receive user defined CAN messages, the I/O
refresh time is not always constant over all PLC cycles. The refresh time
depends on the number of CAN messages matching the identifier filter,
which were received since the previous I/O refresh.
Refer to the PLC Operation Manual for more detailed calculations of the PLC
cycle time.
2-3-2 CAN(open) Interface
This sub-section describes the performance of the physical layer of CAN and
the performance of the CANopen interface of C200HW-CORT21-V1.
The following figure depicts the transmission of CAN messages on the bus.
Message delay time Every message has a certain message delay time, which is mainly
determined by the size of the data field in the message. CAN's bit-stuff
mechanism (after every 5 consecutive equal value bits, a bit of the opposite
polarity is added) can increase the message delay time by a maximum of
15%. The following formulas give the minimum and maximum message
delay time.