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APPENDICES APPENDIX
Appendix 2 Processing Time
Appendix 2 Processing Time
Time chart and communication time of C24 transmission
sequence
The following figure shows a communication time chart when accessing programmable controller from an external device via
C24.
When accessing CPU module with C24 mounted from an external device
The following shows the time chart when the message wait time is specified.
For the number of scans required for processing a read/write request, refer to the following section.
Page 459 Number of scans required for processing
For the number of points processed per communication, refer to the following section.
Page 465 Number of Processing per One Communication
■Reading data
■Writing data
• The communication between C24 and CPU module is always performed after END. Therefore, the scan
time becomes longer according to the communication time (the time to interrupt to the CPU module).
• The number of scans required for processing to request read/write operation to the CPU module differs
depending on the content of the request. For example, when a read operation that requires a scan is
requested, it takes an extra time of 1 scan + T2.
• The number of scans required for the processing varies depending on the Service Processing Setting. It can
be set in the parameter settings of Engineering tool. For details of Service Processing Setting, refer to the
user's manual of the CPU module used.
T0
E
N
Q
S
T
X
END 0 END 0 END 0 END 0 END
T1 T2
T4
C24
External device
Message wait time (TW)
Read
transmission
CPU module
Program
T0
E
N
Q
A
C
K
END 0 END 0 END 0 END 0 END
T1 T2
T4
C24
T3T5
External device
Message wait time (TW)
Checking the RUN/
STOP of the CPU
Write
transmission
Write
transmission
Writing data
CPU module
Program
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