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6 Programming
NJ-series CPU Unit Software User’s Manual (W501)
6-3 Variables
6
6-3-8 Variable Attributes
Use the AT Specification attribute to specify the internal I/O memory address of a variable in memory
used for CJ-series Units. AT specifications are used mainly to specify specific memory addresses for
the following Special Units.
• Addresses in fixed allocations for DeviceNet Units
• Addresses in user-specified allocations for DeviceNet Units or CompoNet Master Units from the CX-
Integrator (A CompoNet Master Unit must be set to communications mode 8 to use the CX-Integra-
tor.)
• Addresses in expansion memory for High-speed Counter Units
• Addresses in expansion memory for Process I/O Units
• Addresses in target node information and user-defined status areas that are used with EtherNet/IP
Units
If this attribute is not set, the variable is automatically assigned to an address in variable memory.
When you assign a device variable to an I/O port, they are automatically given an AT specifica-
tion internally.
Allocation Areas
You can specify addresses in the following areas.
The following table gives the data assignments by variable data type.
AT Specification
Area Expression
CIO CIO 0 to CIO 6143
Work W0 to W511
Holding H0 to H1535
DM D0 to D32767
EM
NJ501-: E0_0 to E18_32767
NJ301-: E0_0 to E3_32767
Variable data type Assignment position
BOOL You can specify an assignment for each bit.
BYTE/SINT/USINT
You can specify bit 0 or bit 8 of the specified CJ-series address as the start
position of the data assignment.
Example 1: AT Specification at Bit 0 of D100 (%D100)
D100: 16#**12....One-byte data (12) is stored from bit 0.
Example 2: AT Specification at Bit 8 of D100 (%D100.8)
D100: 16#12**....One-byte data (12) is stored from bit 8.
WORD/INT/UINT Stored in increments of the data size from bit 0 of the specified CJ-series
address.
DWORD/DINT/UDINT
REAL
LWORD/LINT/ULINT
LREAL
STRING
You can specify bit 0 or bit 8 of the specified CJ-series address as the start
position of the data assignment.
TIME
DATE
TIME_OF_DAY
DATER_AND_TIME
Stored in increments of the data size from bit 0 of the specified CJ-series
address.
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