INDIRECT_RECURSIVE_CALL

Severity: error. PLCopen: CP13 (indirect) — POUs shall not call themselves directly or indirectly.

The call graph contains a cycle of two or more POUs (A → B → A, possibly through more hops). Indirect recursion has the same risk as direct recursion (which is reported by RECURSIVE_CALL): unbounded stack growth on a runtime that is typically single-stack and not designed for it.

Settings. No check-specific config. The cycle is computed against the symbol-table call graph; calls inferred from instance variables (e.g. myFb() where myFb : FB_X) count, as do direct POU calls.

Trigger.

FUNCTION_BLOCK FB_A
VAR fb : FB_B; END_VAR
fb();
END_FUNCTION_BLOCK

FUNCTION_BLOCK FB_B
VAR fa : FB_A; END_VAR
fa();                                  (* fires — FB_A → FB_B → FB_A *)
END_FUNCTION_BLOCK

The bot posts.

🟥 error  INDIRECT_RECURSIVE_CALL
Indirect recursion: FB_A -> FB_B -> FB_A (PLCopen CP13)

Fix. Break the cycle by extracting the shared work into a third POU that both can call without forming a loop.