Application Precautions - Omron CJ1M-CPU21 Operation Manual

Application Precautions

5 Application Precautions
!WARNING
!Caution Failure to abide by the following precautions could lead to faulty operation of
Observe the following precautions when using the PLC System.
• You must use the CX-Programmer (programming software that runs on
Windows) if you need to program more than one cyclic task. A Program-
ming Console can be used to program only one cyclic task plus interrupt
tasks. A Programming Console can, however, be used to edit multitask
programs originally created with the CX-Programmer.
Always heed these precautions. Failure to abide by the following precautions
could lead to serious or possibly fatal injury.
• Always connect to a ground of 100 Ω or less when installing the Units. Not
connecting to a ground of 100 Ω or less may result in electric shock.
• A ground of 100 Ω or less must be installed when shorting the GR and LG
terminals on the Power Supply Unit.
• Always turn OFF the power supply to the PLC before attempting any of
the following. Not turning OFF the power supply may result in malfunction
or electric shock.
• Mounting or dismounting Power Supply Units, I/O Units, CPU Units, or
any other Units.
• Assembling the Units.
• Setting DIP switches or rotary switches.
• Connecting cables or wiring the system.
• Connecting or disconnecting the connectors.
the PLC or the system, or could damage the PLC or PLC Units. Always heed
these precautions.
• A CJ-series CPU Unit is shipped with the battery installed and the time
already set on the internal clock. It is not necessary to clear memory or
set the clock before application, as it is for the CS-series CPU Units.
• The user program and parameter area data in CJ1M CPU Units is backed
up in the built-in flash memory. The BKUP indicator will light on the front
of the CPU Unit when the backup operation is in progress. Do not turn
OFF the power supply to the CPU Unit when the BKUP indicator is lit. The
data will not be backed up if power is turned OFF.
• If, when using a CJ1M CPU Unit, the PLC Setup is set to specify using the
mode set on the Programming Console and a Programming Console is
not connected, the CPU Unit will start in RUN mode. This is the default
setting in the PLC Setup. (A CS1 CPU Unit will start in PROGRAM mode
under the same conditions.)
• When creating an AUTOEXEC.IOM file from a Programming Device (a
Programming Console or the CX-Programmer) to automatically transfer
data at startup, set the first write address to D20000 and be sure that the
size of data written does not exceed the size of the DM Area. When the
data file is read from the Memory Card at startup, data will be written in
the CPU Unit starting at D20000 even if another address was set when
the AUTOEXEC.IOM file was created. Also, if the DM Area is exceeded
(which is possible when the CX-Programmer is used), the remaining data
will be written to the EM Area.
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