Instruction and Application Considerations

When replacing a
ControlLogix
 5560 or
ControlLogix
 5700 controller with a
ControlLogix
 5580 controller or replacing a
CompactLogix
 5370 controller with a
CompactLogix
 5380 controller, there are some changes in the programming languages that may affect your applications. These changes do not affect all programming languages or applications.
The following is a summary of the changes:
  • Math related instructions
    • Truncation changes in TRUNC instructions
    • Improved overall accuracy for ACOS, ASIN, ATAN, COS, LN, LOG, SIN, SQRT, TAN, EXPT
    • SQRT adjustment
    • Relaxed verification rules for AND, NOT, OR, and XOR support for REAL
    • Floating point literals for MAG, MAJ, MAM, MAPC, and MEQ
    • Changed implementation for MOD function and EXPT instruction
    • DIV instruction produces NAN value
  • Structural changes to execution
    • Max number of inputs or outputs for JSR, RET, SBR
    • JSR nesting level limit
    • Max number InOut parameters for Add-On Instructions
    • Add-On Instruction nesting limit
    • JMP instruction requires a corresponding LBL to exist
    • LINT data type in User-Defined Structures
    • MCR instruction must be last instruction in rung
  • Instruction error and faulting changes
    • Subscript expressions are treated separately from instructions
    • TRUNC operator and Math Status Flags
    • Math Status Flags are valid only in one rung
    • Improved accuracy of AVE and STD instructions
    • BTD, FAL, FSC, and CMP instructions no longer generate math status
    • Math Status Flags no longer in structured text
    • Minor fault on overflow
    • Manually set math overflow using OTE or OTL instruction
    • More complete math status flags for TO_BCD instruction
    • Add-On Instructions do not propagate math status flags
    • Subroutines do not affect math status flags
    • ADD and SUB instructions with integer operands can affect the Carry flag
    • NAN value stored as an integer
    • All compares with NAN will be false except for NE
  • Operands changes
    • Writing infinity to an integer is the MAX signed value that is allowed
  • Copy/File Instructions
    • COP and CPS into structures
    • JSR and RET parameters passing into structures
    • JSR passing Atomic data type into an Array or structure
    • AVE, BSL, BSR, DDT, FBC, FFL, FFU, LFL, LFU, SQL, SRT, STD are now limited to member array boundaries
  • Download Workflow Change
    • Using the
      Build
       button on the standard toolbar or downloading a project creates binary files compiled from user subroutines and caches them in the project .ACD file, which can save time when doing subsequent downloads.
    • Only changed source code is recompiled on a download.
Refer to the
Replacement Guidelines:
Logix 5000
 Controllers Reference Manual,
publication
1756-RM100
,
for detailed considerations and explanations of the changes that you may have to make to your project.
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