Omron CJ1W-CORT21 Operation Manual page 109

Example 2
• Number of output buffers: 640
• Number of configured output buffers: 1
Every time the trigger configured message is ON, the evaluation time of all output buffers (being
640) will be: 10.0 + (4.3 * 639) = 2.76 (milliseconds).
Precautions for Correct Use Precautions for Correct Use
To optimize the evaluation time for the triggered send mode, set the number of output buffers
with message command 2902 to the same amount as the number of configured output buffers (
the total number of buffers configured with message command 2903 or 2904).
SM2, On Change Mode
When using On Change mode, the evaluation time differs for output buffers depending on whether they
contain information changes or not. In the case that data in the buffer has changed since the last evalu-
ation, the evaluation time is 52 microseconds. If the output buffer has not changed, the evaluation time
depends on the length of data in all the output buffers and is in the range of 15.4 - 47.0 microseconds.
The given times are for messages using the big endian format. Using little endian format will increase
the evaluation time with approximately 13%.
The total number of output buffers is configured with message command 2902. Message command
2903 and 2904 are used to associate a buffer with an identifier. A buffer with an identifier associated is
called a configured buffer. The evaluation time for buffers that are not configured is 4.3 microseconds.
Example 1
• Number of output buffers: 2
• Number of configured output buffers: 1
Every time the configured message is changed, the evaluation time of all output buffers (being 2) will
be: 52.0 + 4.3 = 56.3 (microseconds).
The evaluation time is 47.0 + 4.3 = 51.3 (microseconds) for output buffers that are not changed
since the last evaluation. The length of the configured output buffer is assumed to be 8 characters.
Example 2
• Number of output buffers: 640
• Number of configured output buffers: 1
Every time the configured message is changed, the evaluation time of all output buffers (being 640)
will be: 52.0 + (4.3 * 639) = 2.8 (milliseconds).
Precautions for Correct Use Precautions for Correct Use
The following guidelines apply to optimizing the evaluation time for the On Change Mode:
• Set the number of output buffers with message command 2902 to the same amount as the
number of configured output buffers (that is the total number of buffers configured with mes-
sage command 2903 or 2904).
• Use the big endian format in message commands 2903 and 2904 whenever possible because
the little endian format will increase the evaluation time.
CJ-series User Defined CAN Unit Operation Manual for NJ-series CPU Unit (W517)
5 Communications Timing
5
5-3