Omron CVM1 Series, Operation Manual

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Replacement Checklists Section 3-6
• The PC Link I/O response characteristics depend on the PLC model. For
example, the PC Link data refreshing of a CVM1/CV-series PLC set for
synchronous mode processing is about one cycle (one instruction execu-
tion cycle) longer than it would be in a C1000H/C2000H PLC.
For details on I/O response times, refer to
Appendix C PC Link System I/
O Response Time .
• When the CPU Unit is set for asynchronous mode processing, the periph-
eral processing cycle is not synchronized with the instruction execution
cycle, so the data in the LR Area may change within an instruction execu-
tion cycle. Consequently, we generally recommend using synchronous
mode processing. Select synchronous operation in the PLC Setup (in the
Execute control 2 settings).
• The I/O response time tends to be longer when using synchronous mode
processing.
Asynchronous mode can be used to reduce the I/O response time, but it
is possible for the content of words to change during execution of an
instruction that accesses many words. To ensure the uniformity of a block
of words, use the DISABLE ACCESS IOSP(187) and ENABLE ACCESS
IORS(188) instructions or the CPU Bus Service Disable Bits in A015 to
prevent the words from being changed by peripheral servicing during
instruction execution.
3-6 Replacement Checklists
This section provides a checklist for PC Link settings when upgrading from a
C500/C1000H/C2000H to a CVM1/CV-series Rack. It is assumed that only
the PLC is being replaced and the basic PC Link system layout and settings
(such as the level settings, number of LR bits/Unit, and node addresses) are
being left unchanged.
Check the system in advance and prepare a system configuration diagram
(showing the models of all PC Link Units and switch settings) and ladder dia-
gram specifications (showing the program specifications in the PLC being
replaced) in advance.
Based on the PC Link system diagram, the replacement pattern can be classi-
fied as pattern A, B, or C. Select the corresponding pattern checklist and
make the necessary settings indicated in the replacement checklist.
Pattern Selection
Flowchart
Check
system configuration.
Contains mid-sized PLCs
(C200H
@ or CS-series).
Single-level LK003 mode
Contains 3G2A5-LK009
PC Link Units.
Pattern A
Pattern A
Pattern B
Pattern C
Contains only large PLCs
(C500/C1000H/C2000H).
Check
PC Link level settings.
Check
PC Link Unit models.
Single-level LK009 mode
or multi-level mode
Contains C500-LK009-V1
PC Link Units only.