Timers
Analog
Others
Counter
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:
Inverting inputs
Block configuration
Reference parameters
Protection
Retentivity
The special functions are organized by group and are listed below:
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Counter |
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| The LAD Editor offers you the following additional functions: |
| FBD and UDF Editors: description of the blocks of special functions |
| The LOGO! version you have selected determines these characteristics of your circuit program:
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Inverting inputs
You can invert individual inputs:
A logical "1" at a specific input is inverted to logical "0" in the circuit program.
A logical "0" is inverted to logical "1" in the circuit program.
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.
Note
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| 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.
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For the LOGO! 0BA7 device, there is a timer reference function. With this function, you can take the current time (Ta) of a timer as the reference value (C) in other function blocks. The calculation of the reference value (C) follows the formula as shown below:
Current time (Ta) | Time base | Reference value (C) |
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A : B | Hours (h : m) | C = A × 60 + B |
A : B | Minutes (m : s) | C = A × 60 + B |
A : B | Seconds (s: 1/100s) | C = A × 100 + B |
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:
on: Current data values are retained
off: Current data values are not retained (default).
The Hours counter is an exception, because it is generally retentive.
