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Data Link I/O Response Time
Section 8-3
CVM1 and CV-series PLCs Under Asynchronous Operation
Maximum Response Time
There are five points shown in the diagram above where processing is
delayed, increasing the data link I/O response time.
1,2,3...
1.
The input arrives in the PLC just after I/O refreshing, causing a delay of up
to one cycle before the input is read into the PLC.
2.
Data exchange occurs just after the PLC at node #1 passes the token that
makes it the polling node, causing a delay of up to one communications cy-
cle time before the data is transferred in data link processing.
3.
At node #7, data from the previous data exchange is still being transferred,
causing a delay of up to one cycle before the input is read into the PLC.
4.
The data transferred in data link processing arrives at the PLC at node #7
after data exchange, so the data will not be read into the PLC until the next
data exchange, causing a delay of up to one peripheral servicing interval.
Up to 3,700 words can be transferred in a single data exchange, so a delay
of another peripheral servicing interval will occur if more than 3,700 words
are being transferred.
5.
The data is received after the PLC at node #7 has executed the instruction,
causing a delay of up to one cycle time.
Controller Link Unit transmission processing
Program
(1)
(2)
(3)
(4)
Input
Input device
Input ON delay
1 cycle
Program
PLC at node #1
PLC at node #7
Data link transmission
Controller Link Unit transmission processing
Communications
cycle time
Output device
Output ON
delay
Output
Data link I/O response time
Peripheral servicing interval
I/O refresh
Previous communica-
tions cycle data
1 cycle
Peripheral servicing interval
Summary of Contents for C200HW-CLK21
Page 3: ...iv ...
Page 9: ...x ...
Page 12: ...xiii TABLE OF CONTENTS Index 367 Revision History 373 ...
Page 13: ...xiv ...
Page 19: ...xx ...
Page 57: ...32 Application Precautions Section 1 5 Example CX Programmer Response Timeout Setting ...
Page 69: ...44 Message Service Procedure Section 2 2 ...
Page 111: ...86 Constructing Networks with Repeater Units Section 3 4 ...
Page 154: ...129 Setting Data Links Section 5 2 Device Information Setting Data Link Tables ...
Page 261: ...236 Response Codes Section 6 7 ...
Page 297: ...272 Message Delay Times Section 8 4 ...
Page 353: ...328 Handling Precautions Section 9 6 ...
Page 364: ...339 Changing the Data Link Tables with Active Data Links Section 10 2 ...
Page 365: ...340 Changing the Data Link Tables with Active Data Links Section 10 2 ...
Page 369: ...344 Standard Models Appendix A ...
Page 391: ...366 Using the Relay Terminal Block Appendix C ...
Page 397: ...372 Index ...
Page 401: ...376 Revision History ...