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3.10
Precautions for Use of File Registers
This section explains the precautions for use of the file registers in the QCPU and LCPU.
CPU modules that cannot use file registers
The Q00JCPU and Q00UJCPU cannot use the file registers. When using the file registers, use the CPU module of other than
the Q00JCPU and Q00UJCPU.
Setting of file registers to be used
When using the file registers, the file registers to be used must be set with the PLC parameter or QDRSET instruction. (The
PLC parameters of the Q00CPU, Q01CPU and LCPU need not be set since they are preset to "Use file register". QDRSET
instructions are not available with LCPU.) If the file registers to be used have not been set, normal operation cannot be
performed with the instructions that use the file registers.
Even when file registers to be used are not set in the PLC parameter, a program that uses file registers can be
created. For the CPU module other than the Universal model QCPU and LCPU, an error does not occur when
that program is written to the CPU module.
However, note that the correct data cannot be written/read to/from the file register.
For the Universal model QCPU and LCPU, an error occurs if the program where file registers are used is
executed.
Securing of file register area
■Basic Model QCPU
The user does not need to secure a file register area, because such a file register area is reserved in advance in the standard
RAM.
■High Performance model QCPU, Process CPU, Redundant CPU, and Universal model QCPU
(except High-speed Universal model QCPU)
Register file registers in the standard RAM/memory card to secure a file register area.
■High-speed Universal model QCPU, and LCPU
Register file registers in the standard RAM to secure a file register area.
For the setting method for file registers and memories available for the file registers of CPU modules, refer to
the User's Manual (Function Explanation, Program Fundamentals) for the CPU module used.
Designation of file register number in excess of the registered number of points
■Basic model QCPU, High Performance model QCPU, Process CPU, and Redundant CPU
An error will not occur if data are written or read to or from the file registers that have numbers greater than the registered
number of points. However, note that the read/write of correct data to/from the file registers cannot be performed.
■Universal model QCPU and LCPU
When data are written to or read from the file registers that are not registered, an error occurs. (Error code: 4101)
3 CONFIGURATION OF INSTRUCTIONS
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3.10 Precautions for Use of File Registers
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