Siemens Simatic S7-300 CPU 31xC Series Installation And Operating Instructions Manual page 144

Commissioning
8.4 Commissioning the Modules
Monitor variable
You have two options for monitoring variables:
• updating the status values once via menu item Variable > Update Status Values
• continuous update of status values via menu item Variable > Monitor
Modifying variables
To modify variables, proceed as follows:
1. Left-click the field Modify value of the relevant variable.
2. Enter the modify value according to the data type.
3. To update modify values once, select the menu item Variable > Activate Modify Value.
4. In the Monitor test function, verify the modify value entry in the variable.
Is the modify value valid?
You can disable the modify value entered in the table. An invalid value is displayed same as
a comment. You can re-enable the modify value.
Only valid modify values can be enabled.
Setting the trigger points
Trigger points:
• The "Trigger point for monitoring" determines the time of update for values of variables to
• The "Trigger point for modifying" determines the time for assigning the modify values to
Trigger condition:
• The "Trigger condition for monitoring" determines whether to update values once when
• The "Trigger condition for modifying" determines whether to assign modify values once or
You can customize the trigger points using the tool "Monitor and modify variable" in menu
item Variable > Set Trigger ... start.
8-20
or
or
Enable modify values permanently via menu item Variable > Modify.
be monitored.
the variables to be modified.
the trigger point is reached or continuously every time the trigger point is reached.
permanently to the variable to be modified.
S7-300, CPU 31xC and CPU 31x: Installation
Operating Instructions, Edition 08/2004, A5E00105492-05