Columns (Properties) in Variables Worksheets

A variables worksheet contains one line for each variable or FB instance declaration. The properties of the declaration are contained in various grid columns.

For editing a particular property directly in the grid, left-click into the corresponding field and type the desired information. In some cases (e.g., for 'Type' and 'Usage') a drop-down combo box opens for selecting an entry.

Column	Meaning
Icon in first table cell	The icon indicates the type of variable: global symbolic variable safety-related input signal safety-related output signal standard input signal standard output signal
Name	Name of the variable/instance. EcoStruxure Machine Expert - Safety allows to use DIN qualifiers in IEC 61131 variable names. Rules for using DIN qualifiers According to the IEC 61131 standard, variable names can consist of letters, digits, and underscores. The identifier has to begin with a letter or an underscore. The use of any other character causes the compiler error "Illegal identifier". This naming convention has been expanded in EcoStruxure Machine Expert - Safety in a way that IEC 61131 variable names may also contain DIN qualifiers: The characters - + < > can be used at any position in the name and as last character. However, they cannot be used as first character of a variable name. The DIN qualifiers / * # and the numbers 0 to 9 can be used at any position in the variable name. Rules for using DIN qualifiers in IEC 61131 variable names Variable names must at least contain one alphabetical character. Variables must not have the name of an IEC 61131 data type, such as BOOL, INT, WORD, REAL, etc. Variable names must not be defined as they are for literal values. Literals are used in the code by first specifying the literal data type, followed by a hash sign: <literal_prefix>#<value>. For example, SAFEINT#5 and WORD#32767 are literals. Therefore, a variable declaration such as safeint#MyVar would be invalid. Literal prefixes are not case-sensitive and include the following keywords: BOOL, REAL, LREAL, SINT, USINT, INT, UINT, DINT, UDINT, LINT, ULINT, BYTE, WORD, DWORD, LWORD, TIME, T, DATE, D, TIME_OF_DAY, TOD, DATE_AND_TIME, DT, STRING, TIMEDATE48, WEIGHT, ANALOG, UNIFRACT, BIFRACT200, FIXED, BOOLEAN2, BCD4, ENUM4, SAFEBOOL, SAFEBYTE, SAFEDWORD, SAFEINT, SAFEDINT, SAFETIME, SAFEWORD The variables grid indicates the following errors: Invalid names, multiple use.
Online Value	Online value of the variable read from the Safety Logic Controller or simulation during runtime (read-only). The column is only visible after the variables worksheet has been switched to online mode and if the grid line does not contain an FB instance declaration. When forcing or overwriting variables in debug mode, the forced/overwritten variable value is visible here. Forced values are shown on a pink background. Also refer to the related topics list below the table.
Data type	Data type of the variable. Data types determine what kind of value a variable can have. The data type defines the initial value, range of possible values, and the number of bits. Selection via drop-down combo box The 'Data type' combo box provides the elementary data types as well as all available FB types for selection. Elementary standard (non-safety-related) data type Elementary safety-related data type User-defined function block used in the present project Standard IEC 61131-defined function block Safety-related function block
Usage	IEC 61131 variable declaration keyword and thus the type of the variable (e.g., input, output, symbolic variable). Selection via drop-down combo box In the 'Usage' combo box, the variable declaration keyword can be selected. The list is context-sensitive. Only keywords are provided for selection which are allowed for the present POU type. VAR (local variable) VAR_IN (input variable of a function block POU) VAR_OUT (output variable of a function block POU) NOTE: In the global variables worksheet, the 'Usage' column is not visible because the keyword is set to VAR_GLOBAL by default. This column is not available in the global variables worksheet because the declaration keyword VAR_GLOBAL automatically applies to all global variables.
Description	User-defined comment. The comment entered here is also visible in the tooltip which appears when hovering the mouse over the respective object in the FBD/LD code.
Terminal	This column is only available in the global variables worksheet. It displays the name of the I/O terminal (physical address) to which the global I/O variable is assigned. After dragging a process data item into a code or variables worksheet, thus connecting the related terminal with a variable (see topic "Assigning variables to process data items"), the descriptive text of the connected process data item is visible in the 'Terminal' field of the global declaration. This terminal description is read from the device description file and cannot be edited. The variable grid indicates the following errors: Assignment to process data items which have been deleted in the mean time as well as multiple assignment.
Init	Initial value (only for variables, not for FB instances). According to IEC 61131-3 standard, initial values can optionally be assigned to variables. The initial value is applied when processing the variable for the first time during runtime. Rules for initializing variables The initial value is optional. If no initial value is specified, the variable is initialized with the default initial value of the data type as defined by IEC 61131-3. Initial values can be specified for local (symbolic) variables and global output variables. Global input variables (global variables which are assigned to a physical input) cannot be initialized. The initial value has to match the selected data type. For Boolean variables, the default initial value is 0 or FALSE. For safety-related variables, initial values must be entered with preceding safety-related data type in the following format: SAFEINT#value, SAFEBYTE#value, SAFEWORD#value, SAFEDWORD#value, or SAFETIME#values. (value represents the proper value, e.g., SAFEINT#13 or SAFETIME#1s.) To initialize a safety-related Boolean variable with FALSE, you can either enter SAFEBOOL#0 or SAFEFALSE. Use accordingly SAFEBOOL#1 or SAFETRUE to preset a safety-related Boolean variable to TRUE. Global variable acts as global constant: if a global symbolic variable has an initial value, it can be considered as a global constant with symbolic name. The initialized global symbolic variable is write-protected and the compiler treats it as a constant. As a result, it can be connected, for example, to a function block formal parameter which expects a constant. Refer to the topic "Inserting Constants".
Confirm	This column is only available in the global variables worksheet. It is only visible if a process data item has been modified. Left-click this checkbox to confirm the modified process data item. Background: This confirmation is required after modifying the bus structure in the EcoStruxure Machine Expert 'Devices' window in a way that results in a different physical address of the related global I/O variable. (For example, by adding, deleting or replacing a device in the external bus configuration tool.)¹
DIAG	This flag is only available for local output variables (usage VAR_OUT) of the data type WORD. If selected, an implicit diagnostic is performed for this particular variable. Background: Safety-related firmware function blocks as well as user-defined FBs in a safety-related project may have a diagnostic output which allows polling of FB status information. This diagnostic information can be written to a reserved output buffer area (DQ buffer) while compiling and further processed, for example, using a diagnostic tool. Select the 'DIAG' flag to add the local output variable (FB output) to the DQ buffer.
Feedback	If this flag is set, the variable is considered as feedback variable. It can be used to program an implicit feedback in the safety logic.² The 'Feedback' flag can only be set in combination with 'Usage = VAR' and 'Scope = Local'. Further Information Refer to topic "Implicit feedbacks in FBD" for further information.

¹	Modifying the bus structure may result in a reassignment of the physical addresses of the devices. You must validate and, if necessary, reallocate the addresses of the related global I/O variables to ensure that the new addresses are correct and consistent.

WARNING

UNINTENDED EQUIPMENT OPERATION

Inspect and correct as necessary any global I/O variable addresses related to physical, safety-related I/Os whenever you modify the bus structure.

Whenever you add, delete or exchange devices in the bus structure, validate the physical wiring of your safety-related architecture and thoroughly test the application.

Failure to follow these instructions can result in death, serious injury, or equipment damage.

²	When programming implicit feedbacks, the safety logic may be constantly preempted by the updating of the feedback, which may result in a complex timing of your entire application.

WARNING

UNINTENDED EQUIPMENT OPERATION

Verify the impact of programmed implicit feedbacks particularly with respect to their effect on the performance of your application.

Make certain that suitable organizational measures (according to applicable sector standards) have been taken to avoid hazardous situations if the safety logic application operates in an unintended or incorrect way.

Do not enter the zone of operation while the machine is operating.

Ensure that no other persons can access the zone of operation while the machine is operating.

Observe the regulations given by relevant sector standards while the machine is running in any other operating mode than "operational".

Use appropriate safety interlocks where personnel and/or equipment hazards exist.

Failure to follow these instructions can result in death, serious injury, or equipment damage.