340 • The UTIL.LIB Library

Signal generators

14.5.3PID

The PID controller function block:

ACTUAL (actual value) and DESIRED (desired or nominal value) as well as KP, the proportionality coefficient, are all input values of the type REAL. TR, the integral action time, and TD, the derivative action time, are delivered in msec by a DWORD. RESET is of the type BOOL and serves to reset the controller.

The output, the absolute control output (OUT), is of the type REAL, and is calculated as follows:

whereby =DESIRED-ACTUAL.

The PID controller can be easily converted to a PI controller by setting TD=0.

Example in FBD:

14.6 Signal generators

14.6.1BLINK

The function block BLINK generates a pulsating signal. The input consists of ENABLE of the type BOOL, as well as TIMELOW and TIMEHIGH of the type TIME. The output OUT is of the type BOOL.

If ENABLE is set to TRUE, BLINK begins, to set the output for the time period TIMEHIGH to TRUE, and then afterwards to set it for the time period TIMELOW to FALSE.

Example in CFC:

WAGO-I/O-SYSTEM 759 WAGO-I/O-PRO 32

14.6.2GEN

The function generator generates typical periodic functions:

The inputs are a composition consisting of MODE from the pre-defined counting type GEN_MODE, BASE of the type BOOL, PERIOD of the type TIME, of two INT values CYCLES and AMPLITUDE and of the BOOLean RESET input.

The MODE describes the function which should be generated, whereby the enumeration values TRIANGLE and TRIANGLE_POS deliver two triangular functions, SAWTOOTH_RISE an ascending, SAWTOOTH_FALL a descending sawtooth, RECTANGLE a rectangular signal and SINE and COSINE the sine and cosine:

TRIANGLE: TRIANGLE_POS:

SAWTOOTH_RISE: SAWTOOTH_FALL:

RECTANGLE: SINUS:

COSINUS:

BASE defines whether the cycle period is really related to a defined time (BASE=TRUE) or whether it is related to a particular number of cycles, which means the number of calls of function block (BASE=FALSE).

WAGO-I/O-SYSTEM 759 WAGO-I/O-PRO 32