Omron CJ Series Operation Manual page 28

Precautions for Safe Use
The Power Supply Unit may continue to supply power to the rest of the Controller for a few seconds
after the power supply turns OFF. The PWR indicator is lit during this time. Confirm that the PWR
indicator is not lit before you perform any of the above.
Operation
• Confirm that no adverse effect will occur in the system before you attempt any of the following.
• Changing the operating mode of the CPU Unit (including changing the setting of the Operating
Mode at Startup)
• Changing the user program or settings
• Changing set values or present values
• Forced refreshing
• Always sufficiently check the safety at the connected devices before you change the settings of an
EtherCAT slave or Special Unit.
• If two different function modules are used together, such as when you use CJ-series Basic Output
Units and EtherCAT slave outputs, take suitable measures in the user program and external controls
to ensure that safety is maintained in the controlled system if one of the function modules stops. The
relevant outputs will stop if a partial fault level error occurs in one of the function modules.
• Always confirm safety at the connected equipment before you reset Controller errors with an event
level of partial fault or higher for the EtherCAT Master Function Module.
When the error is reset, all slaves that were in any state other than Operational state due to a Con-
troller error with an event level of partial fault or higher (in which outputs are disabled) will go to Oper-
ational state and the outputs will be enabled.
Before you reset all errors, confirm that no Controller errors with an event level of partial fault have
occurred for the EtherCAT Master Function Module.
• Always confirm safety at the connected equipment before you reset Controller errors for a CJ-series
Special Unit. When a Controller error is reset, the Unit where the Controller error with an event level
of observation or higher will be restarted.
Before you reset all errors, confirm that no Controller errors with an event level of observation or
higher have occurred for the CJ-series Special Unit. Observation level events do not appear on the
Controller Error Tab Page, so it is possible that you may restart the CJ-series Special Unit without
intending to do so.
You can check the status of the _CJB_UnitErrSta[0,0] to _CJB_UnitErrSta[3,9] error status variables
on a Watch Tab Page to see if an observation level Controller error has occurred.
Battery Backup
• The user program and initial values for the variables are stored in non-volatile memory in the CPU
Unit. The present values of variables with the Retain attribute and the values of the Holding, DM, and
EM Areas in the memory used for CJ-series Units are backed up by a Battery. If the Battery is not
connected or the Battery is exhausted, the CPU Unit detects a Battery-backup Memory Check Error.
If that error is detected, variables with a Retain attribute are set to their initial values and the Holding,
DM, and EM Areas in memory used for CJ-series Units are cleared to all zeros. Perform thorough
verifications and provide sufficient measures to ensure that the devices perform safe operation for the
initial values of the variables with Retain attributes and the resulting operation.
Debugging
• Forced refreshing ignores the results of user program execution and refreshes I/O with the specified
values. If forced refreshing is used for inputs for which I/O refreshing is not supported, the inputs will
first take the specified values, but they will then be overwritten by the user program. This operation
differs from the force-set/reset functionality of the CJ-series PLCs.
• You cannot upload or download information for forced refreshing with the Sysmac Studio.
After downloading data that contains forced refreshing, change to RUN mode and then use the Sys-
mac Studio to perform the operation for forced refreshing.
Depending on the difference in the forced status, the control system may operate unexpectedly.
26 CJ-series CompoNet Master Unit Operation Manual for NJ-series CPU Unit (Cat. No. W493)