Omron CJ1W-ECT21 Operation Manual page 19

Turning OFF the Power Supply
• Never turn OFF the power supply to the Controller when the BUSY indicator is flashing. While the
BUSY indicator is lit, the user program and settings in the CPU Unit are being backed up in the
built-in non-volatile memory. This data will not be backed up correctly if the power supply is turned
OFF. Also, a major fault level Controller error will occur the next time you start operation, and opera-
tion will stop.
• Do not turn OFF the power supply or remove the SD Memory Card while SD Memory Card access is
in progress (i.e., while the SD BUSY indicator flashes). Data may become corrupted, and the Control-
ler will not operate correctly if it uses corrupted data. To remove the SD Memory Card from the CPU
Unit while the power supply is ON, press the SD Memory Card power supply switch and wait for the
SD BUSY indicator to turn OFF before you remove the SD Memory Card.
• Do not disconnect the cable or turn OFF the power supply to the Controller when downloading data
or the user program from Support Software.
• Always turn OFF the power supply to the Controller before you attempt any of the following.
a) Mounting or removing I/O Units or the CPU Unit
b) Assembling the Units
c) Setting DIP switches or rotary switches
d) Connecting cables or wiring the system
e) Connecting or disconnecting the connectors
• Do not touch the terminals on the Power Supply Unit immediately after turning OFF the power supply.
Residual voltage may cause electrical shock.
• Never turn OFF the power supply to the Controller until RUN mode is entered after the power is
turned ON. If the power supply is turned OFF, a Battery-backup Memory Check Error may occur at
next time you start operation. If a Battery-backup Memory Check Error occurs, the variables retained
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. If you want to resume the operation, reload the correct data for the variables
retained and CJ-series Unit memory, as required.
Operation
• Confirm that no adverse effect will occur in the system before you attempt any of the following.
a) Changing the operating mode of the CPU Unit (including changing the setting of the Startup
Mode)
b) Changing the user program or settings
c) Changing set values or present values
d) Forced refreshing
• If two different function modules are used together, such as when you use CJ-series Basic Units and
EtherCAT slaves, 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 out-
puts will behave according to the slave or Unit specifications 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 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.
• After you change any slave or Unit settings, carefully check the safety of the controlled system before
you restart the Unit.
CJ-series EtherCAT Slave Units Operation Manual for NJ-series CPU Unit (W542)
Precautions for Safe Use
17