Special functions - Overview

image\icon_sonderfunktionen_sn.gif

This tool has to be selected if you want to place additional retentive or time-related function blocks on the programming interface. The specific type of block is selected from an additional toolbar that opens when you select the SFB tool.

This topic also describes the following tasks or characteristics of the special functions:

The special functions are organized by group and are listed below:

 

Timers

image\toolbar_special_functions_esv.gif On-delay

image\toolbar_special_functions_asv.gif Off-delay

image\toolbar_special_functions_asvesv.gif On-/Off-delay

image\toolbar_special_functions_sesv.gif Retentive on-delay

image\toolbar_special_functions_wischi.gif Wiping relay (pulse output)

image\toolbar_special_functions_wischf.gif Edge triggered wiping relay

image\toolbar_special_functions_symtakt.gif Symmetrical pulse generator

image\toolbar_special_functions_asynig.gif Asynchronous pulse generator

image\toolbar_special_functions_zufall.gif Random generator

image\toolbar_special_functions_tls.gif Stairway light switch

image\toolbar_special_functions_komfs.gif Multiple function switch

image\toolbar_special_functions_wochen.gif Weekly timer

image\toolbar_special_functions_jahr.gif Yearly timer

 

Counters

image\toolbar_special_functions_vorrueck.gif Up/Down counter

image\toolbar_special_functions_betrsz.gif Hours counter

image\toolbar_special_functions_sws.gif Threshold trigger

Analog

image\toolbar_special_functions_anasws.gif Analog threshold trigger

image\toolbar_special_functions_anadiffss.gif Differential analog trigger

image\toolbar_special_functions_anak.gif Analog comparator

image\toolbar_special_functions_anadwue.gif Analog value monitoring

image\toolbar_special_functions_anav.gif Analog amplifier

image\toolbar_special_functions_mux.gif Analog multiplexer

image\toolbar_special_functions_pwm.gif Pulse width modulator (PWM)

image\toolbar_special_functions_analogmath.gif Analog math

 

Control and Regulate

image\toolbar_special_functions_pi.gif PI controller

image\toolbar_special_functions_ramp.gif Ramp control

 

Others

image\toolbar_special_functions_selbsthalter.gif Latching relay

image\toolbar_special_functions_stroms.gif Pulse relay

image\toolbar_special_functions_melde.gif Message text

image\toolbar_special_functions_softs.gif Softkey

image\toolbar_special_functions_schiebe.gif Shift register

image\toolbar_special_functions_analogmatherror.gif Analog math error detection

 

 

image\lad_fbd_logo_sn.gif

The LAD Editor offers you the following additional functions:

AND with edge evaluation

NAND with edge evaluation

image\lad_fbd_logo_sn.gif

FBD editor: description of the blocks of special functions

The description of the blocks of special functions in the circuit diagram begins with timer blocks (“T”), with counter blocks (“C”) and with the remaining blocks (“SF”).

 

image\0ba3_logo_sn.gif

The LOGO! version you have selected determines these characteristics of your circuit program:

  • Available blocks

  • Parameters that you can set

 

Inverting inputs

You can invert individual inputs:

To do so, right-click on the input and select the invert command from the shortcut menu.

You cannot invert the inputs of output blocks.

 

image\0ba3_logo_sn.gif

0BA0-0BA3:

To invert an input, use the basic function NOT.

Block configuration

The block properties dialog provides you with an easy means of setting the various block parameters.

Reference functionality

You can also assign parameters to blocks by means of other blocks. Such parameters are called reference parameters.

If you click on the Reference button next to a parameter in the block properties window, you can select which other block provides the actual value for that parameter. For example, if you click the Reference button for the Off-Delay parameter of an Off-Delay timer, you can then choose a specific block to use to provide the time value of the timer. LOGO!Soft Comfort displays the set of available blocks in your circuit program that you can use to provide the reference parameter.

This way it is possible, for example, to assign the time of an off-delay timer from an analog output value from another block.

 

image\tricks_logo_sn.gif

A quick way of changing block parameters

Protection

If a Protection Active check box exists for the protection of a block parameter, you can enable or lock the display and editing of this parameter in LOGO! configuration mode.

Retentivity

The switching state and counter values of SFBs can be retentive. This means that the current data values are retained, for example after a power failure, so that the function is resumed at the break position after power on. Hence, a timer is not reset, but instead the time-to-go expires.

However, to enable this feature for the relevant function, retentivity needs to be set. There are two possible settings:

The hours counter is an exception, because it is generally retentive.