The VisXpert module VarSniffer allows you to observe and control variables. Predefined variables of the modules “Memory” and “SPS data” can be accessed. In addition, it is possible to enter so-called direct variables. That is, after defining a group, a variable can be determined by defining a corresponding operand.

  • Both predefined and direct variables are possible.
  • Several variables can be stored and reloaded in a list.
  • Depending on the variable type, different display formats are possible, such as decimal and hexadecimal.
  • Blocks can also be observed and controlled.
  • Several variables can be changed and then controlled at the same time.
  • Disturbances of individual variables are displayed in color.
  • Incomplete or incorrect information is marked.
  • The entire variable check and connection with the communication module takes place immediately after leaving the currently edited line, i.e. there is no difference between editing and processing.

User Interface

 The main window of the VarSniffer shows as follows:



The variable group predefined in a driver.


The variable name from a driver or as a direct variable.


The VisXpert variable type: There are also the following 5 types to choose from:

For direct variables, the Vartype can be changed depending on other inputs.


Specifies the length (size) of the variable. There are certain conditions to be observed, which are set out in detail in the Annex. An incorrect input is displayed.

Format: (Display format)

The format depends on the VisXpert variable type. For example, an integer number can be represented in dual, decimal, or hexadecimal.

Entering Data

In “Group” you select a group from the drop-down box. If this is an S5 or S7 group, you can
enter the operand directly in the “Name” field. Such as. “db200 dw0” is sufficient. Provided that this DB can be controlled (i.e. DB must be present in the AG), and the fact that the VarType and Length columns are filled can be displayed in the values of this so-called “direct variable”. You click on the column “Name” and select a variable via the selection dialog that then appears:

The variables listed are the ones predefined in the drivers. In addition, already entered direct variables appear, which are recognizable by the “A”. The information is transferred to the VarSniffer main window together with the invisible length.

If you select the Direct Variable tab, the following picture shows:

If an S5 or S7 group is selected, direct variable input is possible.

The check box “from data block” determines whether an entry is possible for “DB-Nr” and fills the combo box at “Address” with the corresponding entries, depending on the PLC type. The remaining Variables Type, Length, and Display Format inputs correspond to the fields in the main window.

After the input is taken, direct variables are always checked for the variable name and any errors are displayed in the main window.

Loading and saving

If you have defined several variables, which are often related to each other, they can be saved in a list and reloaded if necessary. This can be achieved by pressing the buttons with the known symbols.

Observing and controlling variables

The “current value” field shows the current value of the variable in the respective display format.
The update occurs after the value changes.

For all VisXpert variable types except data blocks, enter the desired value in the Setpoint column and leave the column. If the value is different from the current value, the tax value turns light blue. Now you can enter additional control values or write this value with the “Control” or F2 key for control. If you have changed several values, they can all be changed together with the “Apply all” button or Ctrl+F2. Attention: The plausibility of data entry is not checked.

Since data blocks cannot be clearly displayed in the main window due to their size, you can switch to an extended display with the Detail button: Here blocks can be edited clearly. With “Taxes” the data is written immediately, with “Apply” it is transferred to the main window in the column Tax value. A block length check and valid characters are checked. 

“Invalid” variables

If a variable is not (more) valid (e.g. Connection cable disconnected, PLC assembly faulty, etc.), the corresponding variables are colored red:

The “current value” is <nil>displayed because the variable no longer has a defined state.</nil>

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