Omron SYSMAC CS Series User Manual

171
Fail-safe Countermeasure Guidelines Section 3-6
Restrictions in Data
Continuity when
Switching Operation
The Process-control CPU Unit (CS1D-CPU@@P) cannot synchronize data
between the active and standby Loop Controllers for the following ITEMs and
HMI.
If any of the following data is used in calculations in the Loop Controllers or
read using the ladder program in the CPU Unit, calculation results using this
data will not necessarily be the same in the active and standby Boards, or the
data read from the active Board will not necessarily be the same as the data
read from the standby Board.
If operation is switched to the standby Board when the following data is used
in calculations or to control operation, continuity of the results may be lost. Do
not use the following data in calculations or read it using the ladder program in
a way that will affect operation, e.g, to stop operation at a specific time or to
output an alarm at a specific load rate.
ITEM Data That Is Not
Synchronized
The following ITEMs in the System Common block (Block Model 000) are not
synchronized.
• ITEMs 031 to 036: Date and time data (year, year/month, month/day,
hours/minutes, minutes/seconds)
• ITEMs 047 and 048: LCB load factor and LCB maximum load factor
• ITEMs 099 to 110: Memory processing (Backup start command, Recov-
ery start command, Backup error display, Flash memory write count dis-
play, etc.)
HMI Data That Is Not
Synchronized
The following HMI data is not synchronized.
•EM@_00001: LCB load rate
•EM@_00003: LCB maximum load rate
Restrictions on
Startup Mode
The Process-control CPU Unit (CS1D-CPU@@P) cannot specify the startup
mode when power is turned ON. In other words, ITEM018 (START mode at
power ON) in the System Common block cannot be set to 3 (Specification
from CPU Unit).
Restrictions on
Duplex Unit Initial
(INIT) Switch
Operation
With a Process-control CPU Unit (CS1D-CPU@@P), the Duplex Unit's Initial
(INIT) switch cannot be pressed while the active Loop Controller's RDY indica-
tor is not lit (*1). Wait until the RDY indicator is lit for both Loop Controllers
before pressing the initial (INIT) switch
*1 When replacing standby CPU Units and Loop Controllers, the RDY indica-
tor will not be lit until approximately 10 seconds after the Duplex Unit's
CPU USE/NO USE switch is set to “USE.”
3-6 Fail-safe Countermeasure Guidelines
Implement fail-safe countermeasures on the Loop Controller according to the
following guidelines.
3-6-1 Measures When the Loop Controller Has Stopped Running
When the Loop Controller stops running, the state before the stop occurred is
held and all operations that were being executed on the Loop Controller are
stopped. Refreshing between the CPU Unit and the function blocks on the
Loop Controller is also stopped. For this reason, the values of the allocated
areas on the Analog Output Unit and the Contact Output Unit whose refresh-
ing cycle was changed are held at the state before the stop occurred by the
AO and DO terminals of the Field Terminal block.

Omron SYSMAC CS Series Specifications

General

Brand	Omron
Model	SYSMAC CS Series
Category	Controller
Language	English