P9997

Code

P9997

Message

Capability is not supported

Compiling the IEC 61131-3 source failed because the program needs a capability that the IronPLC compiler does not offer and does not plan to offer. This is usually a fixed limit of the bytecode format rather than a missing feature.

This differs from P9999, which reports a capability that is not implemented yet. A later release is expected to accept a program that produces P9999. A program that produces P9997 has to change, because the limit it reached is part of the design.

Example

Each variable occupies a run of 8-byte slots in the data region, and the compiler addresses a slot with a 32-bit index. A single variable may therefore occupy at most 32768 slots. The following declaration asks for far more, so it produces error P9997:

TYPE Item : STRUCT
  a : DINT;
  b : DINT;
END_STRUCT;
END_TYPE

PROGRAM main
  VAR
    readings : ARRAY[1..40000] OF Item;
  END_VAR
END_PROGRAM

Each Item occupies 2 slots, so the array needs 80000 slots — more than twice the limit.

To fix this error, reduce the amount of data the variable holds. Splitting the data across several variables works because the limit applies to each variable separately:

TYPE Item : STRUCT
  a : DINT;
  b : DINT;
END_STRUCT;
END_TYPE

PROGRAM main
  VAR
    readings : ARRAY[1..8000] OF Item;
  END_VAR
END_PROGRAM

Limits that produce this error

  • a single variable occupying more than 32768 slots

  • a data region larger than 2 GiB

  • an array whose element count, slot count, or byte size overflows the compiler’s internal arithmetic

If your program needs more than one of these limits allows, please describe what you are building in a GitHub issue — the limits are design choices, and a concrete use case is what would prompt revisiting one.

Think IronPLC is wrong about this?

If you believe this diagnostic is incorrect, open an issue on GitHub with a small sample that demonstrates the problem.