Lenze PLC Designer PLC Designer (R2-x) - Manual (Page 229)

L-force | PLC Designer
The Individual Components

DMS 3.2 EN 02/2011 TD29 227
6.6.16 'Online' 'Force values'
Shortcut: <F7>
With this command, one or more variables are permanently set (see 'Online' 'Write
values' for setting only once at the beginning of a cycle) to user-defined values. The
setting occurs in the run-time system, both at the beginning and at the end of the
cycle.
The time sequence in one cycle: 1.Read inputs, 2. Force values 3. Process code, 4. Force
values 5. Write outputs.
The function remains active until it is explicitly suspended by the user (command
'Online' 'Release force') or the programming system is logged-out.
For setting the new values, a writelist is first created, just as described under 'Online'
'Write values'. The variables contained in the writelist are accordingly marked in
Monitoring. The writelist is transferred to a forcelist as soon as the command 'Online'
'Force values' is executed. It is possible that an active forcelist already exists, in which
case it is updated as required. The writelist is then emptied and the new values
displayed in red as 'forced'. Modifications of the forcelist are transferred to the
program with the next 'Force values' command.
Note!
The forcelist is created at the first forcing of the variables contained in the writelist,
while the writelist existed prior to the first writing of the variables that it contains.
The command for forcing a variable, which means that it will be entered into the
forcelist can be found at the following places:
• Command 'Force Values' in the menu 'Online'.
• Button 'Force Values' in the dialog 'Editing the writelist and the forcelist'.
Note!
In the sequential function chart language, the individual values from which a
transition expression is assembled cannot be changed with 'Force values'. This is
due to the fact that in monitoring the 'Total value' of the expression, not the values
of the individual variables are displayed (e.g. "a AND b" is only displayed as TRUE if
both variables actually have the value TRUE).
In FBD, on the other hand, only the first variable in an expression, used for example as
input to a function block, is monitored. Thus a 'Force values' command is only possible
for this variable.