Reading And Writing Of System Variables; Polynomial Evaluation (Synfct) - Siemens SINUMERIK 840D sl Function Manual

Detailed description
3.7 Actions in synchronized actions
3.7.2

Reading and writing of system variables

The system variables of the NC are listed in the "System Variables" Parameter Manual with
their respective properties. System variables that can be read or written in the action part of
synchronized actions are marked with an "X" in the corresponding line (Read or Write) of the
"SA" (synchronized action) column.
Note
System variables used in synchronized actions are implicitly read and written synchronous to
the main run.
References:
System Variables Parameter Manual
3.7.3

Polynomial evaluation (SYNFCT)

Application
A variable that is evaluated via a polynomial can be read with the SYNFCT function in the main
run and the result can be written to another variable. Application examples:
● Feedrate as a function of drive load
● Position as a function of a sensor signal
● Laser power as a function of path velocity
Syntax
SYNFCT(<Poly_No>,<SysVar_Out>,<SysVar_In>)
Meaning
Parameter
<Poly_No>:
<SysVar_Out>:
<SysVar_In>:
For information on FCTDEF, see Chapter "Polynomial coefficients, parameters ($AC_FCT ...)
(Page 43)"
Example: Additive override of the path feedrate
An override value is added to the programmed feedrate (F word):
68
Meaning
Number of the polynomial defined with FCTDEF:
f(x) = a + a x + a x + a
2
0 1* 2* 3*
System variable, output:
<SysVar_Out> = f(x)
System variable, input:
x = <SysVar_In>
x
3
Function Manual, 08/2018, 6FC5397-5BP40-6BA2
Synchronized actions