psm2001

ST Language

11 posts in this topic

Where i can find the sintax and instrutions of Function Blocks ST Language?

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This is the quickstart. I'll see if I can find the operation manual for FB-ST. Intro to FB @ MrPLC.com

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Try Help \ Index \ Structured Text Commands. There is a list of supported commands there, complete with examples, which show construction, syntax, and give an explanation of how they work. Unfortunately, the examples given in the help, is incomplete, as there are no examples for the numerical functions... i.e. Any_REAL := SIN (MyREAL) ; If I can find time, I'll try to put together a list of examples...

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Here is a list of the Numerical functions that are not given examples in the Help. (Did you find the others in the Help?). VAR1 := ABS (VAR2) ; Returns absolute value (Negative becomes positive). VAR1 and 2 can be Any_INT or Any_REAL (both must be the same) For SQRT, LN, LOG, EXP, SIN, COS, TAN, ASIN, ACOS, or ATAN... VAR1 := SQRT(VAR2) ; VAR1 and 2 can be Any_REAL (both must be the same) SQRT – Returns Square Root LN – returns Natural Log LOG – returns Logarithm EXP – returns Natural exponential SIN – returns Sine as radians COS - returns Cosine as radians TAN - returns Tangent as radians ASIN – returns Arc-sine as radians ACOS - returns Arc-cosine as radians ATAN - returns Arc-tangent as radians Hope this helps

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Is it possible to create a positive or negative edge in ST language ?

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Posted (edited)

No... but you can emulate it using internal memory. CMIIW

IF Input = TRUE THEN
     IF EdgeDetect = FALSE THEN
          'Do "Something", anything you want do be done with the program
          EdgeDetect := TRUE;     'This will ensure the "Something" will be called only once
     END_IF;
ELSE
     EdgeDetect := FALSE;     'This will resets the edge detection
END_IF;

Edited by innoaloe

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Posted (edited)

More ideas. Trigger oneshot with differentiated instruction for EN input OR handle oneshot with internal latch within ST.

EdgeDetect_Example_1.cxp

Edited by BITS N BYTES
Better examples

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This can work in any language. Important thing here is that flag used to store information must be static...

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R_TRIG and F_TRIG function blocks can be used in ST.  They are edge triggers in the Sysmac platform.  You didn't state what PLC.

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