Operation; Battery Backup - Omron NJ501-1 Series User Manual

Precautions for Safe Use
• Setting DIP switches or rotary switches
• Connecting cables or wiring the system
• Connecting or disconnecting the connectors
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 Startup
Mode)
• Changing the user program or settings
• Changing set values or present values
• Forced refreshing
• After you change any slave or Unit settings, carefully check the safety of the controlled system before
you restart the Unit.
• 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 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 or restart a slave, 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.
• The absolute encoder home offsets are backed up by a Battery. If the CPU Unit detects a low battery
voltage or the absence of a mounted battery when the power supply to the Controller is turned ON,
the absolute encoder home offsets are cleared to zeros and an Encoder Home Offset Read Error
occurs. Reset the error and perform homing to define home. If you do not define home, unintended
operation of the controlled system may occur.
20 NJ-series CPU Unit Hardware User's Manual (W500)