Siemens SIMATIC S7-1200 Function Manual page 511

Reaction to error
The Polyline instruction detects different errors that may occur during interpolation
calculation. The result of the interpolation calculation can be output at the output despite a
pending error. If an error prevents correct calculation of the interpolation result, a substitute
output value is output at the output.
You specify the substitute output value that is output if an error occurs that prevents correct
calculation of the interpolation result as follows at the ErrorMode tag:
● If the ErrorMode tag is set to 0, Polyline outputs the input value at the Input parameter.
● If the ErrorMode tag is set to 1, Polyline outputs the substitute output value. You assign
the substitute output value at the SubstituteOutput parameter.
● If the ErrorMode tag is set to 2, Polyline outputs the last valid output value at the Output
parameter.
The Error parameter indicates if an error is pending. When the error is no longer pending,
Error is set to FALSE. The ErrorBits parameter shows which errors have occurred. ErrorBits
is retentive and is reset only by a positive edge at the Reset or ErrorAck parameter.
PID control
Function Manual, 03/2017, A5E35300227-AC
Instructions
9.5 Polyline
511