{"id":"iec-f-trig","model_id":"F_TRIG","name":"CODESYS F_TRIG","summary":"F_TRIG is a function block that detects a falling edge of a Boolean signal. It has a Boolean input CLK and a Boolean output Q; Q becomes TRUE when a falling edge is detected. The source shows Structured Text declaration and call examples using an instance of the function block.","study_notes":["Example declaration: FTRIGInst : F_TRIG;","The source shows the call FTRIGInst(CLK := VarBOOL1); and reading the result as VarBOOL2 := FTRIGInst.Q;"],"safety_notes":[],"sources":[{"url":"https://infosys.beckhoff.com/content/1033/tcplclib_tc2_standard/74390027.html","title":"Beckhoff Information System","accessed":"2026-10-26"},{"url":"https://content.helpme-codesys.com/en/libs/Standard/Current/Trigger/F_TRIG.html","title":"CODESYS Group","accessed":"2026-10-26"}],"verification":{"status":"source_checked","checked_at":"2026-10-26","values":9,"method":"llm_source_check"},"updated_at":"2026-10-26","type":"instruction","spec":{"language":"iec_61131_3","code":"F_TRIG","group":"Trigger","syntax":"FTRIGInst(CLK := VarBOOL1); VarBOOL2 := FTRIGInst.Q;","parameters":[{"name":"CLK","data_type":"BOOL","description":"Input: Boolean signal to be checked."},{"name":"Q","data_type":"BOOL","description":"Output: TRUE when a falling edge is detected."}],"dialect":"CODESYS","related":[],"standards":[]},"url":"https://machineschema.com/instruction/iec-f-trig","license":"https://creativecommons.org/licenses/by/4.0/"}