Instruction behavior changes
The imported logic might contain instructions whose behavior has changed from the version of the
Logix Designer
application from which the logic was exported. The following table lists behavior changes that occur for certain instructions between Logix Designer
release 27 and later releases.Behavior change | Description |
Add-On Instruction nesting level limit | The nesting limit for Add-On Instructions in Logix Designer release v28 is 25 levels deep. The nesting limit for Add-On Instructions in Logix Designer releases v29 and later is 16 levels deep. |
Max number of InOut parameters for Add-On Instructions | The limit on the number of InOut parameters that can be passed into or out of an Add-On Instruction is 64. |
Jump to Subroutine (JSR) nesting level limit | The nesting limit for routines in releases v28 and later is 25 levels deep. |
Routine length limit | In releases v28 and later, the controller limits the number of rungs and structured text lines in a single routine to 10,000. |
Max number of inputs or outputs for Jump to Subroutine (JSR) and Return (RET) instructions | In releases v28 and later, the limit on the number of parameters that can be passed in a JSR or RET instruction is 40 input parameters plus 40 output parameters. A User-defined Data Type (UDT) or array can count as one input or one output parameter. |
Jump-to label must be present before downloading or accepting edits | In releases v28 and later, jump-to labels must exist before a project can be downloaded if working offline or before accepting edits if working online. |
A Master Control Reset (MCR) instruction must be the last instruction on the rung | If a rung of logic contains a Master Control Reset (MCR) instruction, the MCR instruction must be the last instruction on that rung. |
Math status flags are valid only in one line | In releases v28 and later, the math status flag must be positioned after an instruction that can set the math status flag. It cannot be the first instruction in a rung or line of structured text. The math status flag reflects only math status errors that occur on that rung or line of structured text. If a math status flag appears at the beginning of a rung or line of structured text, the logic will not validate. |
Accept Pending Edits accepts all rungs if there are no verification errors but rejects all rungs if there are any errors | In releases v28 and later, when you edit multiple rungs and select Accept Pending Edits , the Logix Designer application accepts or rejects all the edited rungs based on verification errors:
In previous releases, the Logix Designer application accepts the rungs that do not contain verification errors, but does not accept the rungs that contain verification errors. |
Additional behavior changes occur for some instructions when you replace a for detailed considerations and explanations of the changes that you may have to make to your project when replacing controllers.
ControlLogix
5560 or ControlLogix
5700 controller with a ControlLogix
5580 controller or replace a CompactLogix
5370 controller with a CompactLogix
5380 controller. Refer to the Replacement Guidelines:
publication Logix 5000
Controllers Reference Manual, 1756-RM100
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