Omron CS1D DUPLEX SYSTEM - 10-2009 Operation Manual page 486

Online Replacement of I/O Units, Special I/O Units, and CPU Bus Units
450
2. Before removing a Unit during operation without a PLC Programming De-
vice (CX-Programmer or a Programming Console), always confirm that the
Unit Removal without a Programming Device or Removal/Addition of Units
without a Programming Device function has been enabled in the PLC Set-
up. If a Unit is mistakenly removed without enabling the function in the PLC
Setup, an I/O bus error will occur and the PLC (CPU Unit) will stop operat-
ing.
When this function is enabled in the PLC Setup, the Unit Replacement
without a Programming Device Enabled Flag (A09911) will be ON. This
flag can be used to confirm that the required PLC Setup setting has been
made.
Example
Indicator shows that Unit
removal without a Programming
Device is enabled.
Indicator controlled by A09911.
Program example
A09911
Maintenance Start Bit (A80015)
When the Unit Removal without a Programming Device function is selected
and a Unit is removed without a PLC Programming Device, one of the follow-
ing non-fatal errors will be generated depending on the type of Unit that was
removed. The PLC (CPU Unit) will not stop operating even if one of these
non-fatal errors occurs.
Unit type
Basic I/O Unit
Special I/O Unit
CPU Bus Unit
The Maintenance Start Bit is provided to prevent a non-fatal error from occur-
ring even if a Unit is removed without a Programming Device.
When you don't want a non-fatal error to be generated, turn this bit ON before
removing the Unit.
This bit can be turned ON externally (just like the Online Replacement Com-
pleted Bit) by allocating the bit to an external switch on an Input Unit and
inputting the signal or turning ON the bit from a PT. (The bit can also be
turned ON from the CX-Programmer or a Programming Console.)
Note Do not turn ON the Maintenance Start Bit (A80015) continuously from the lad-
der program or other source. As long as the Maintenance Start Bit is ON,
errors will not be generated even if there are Unit malfunctions, so the system
may be adversely affected.
Output to LED
A09911 is allocated to a PT
indicator.
Non-fatal error
Basic I/O Unit error
Special I/O Unit error
CPU Bus Unit error
Section 11-4
Enable Unit removal without a
Programming Device in the PLC Setup.
A09911 is the Unit Removal without a
Programming Device Enabled Flag.
PT
Setting enabled