PLC commissioning
6.7 Testing the PLC program
Manual
Commissioning Manual, 05/2008, 6FC5397–4CP10–4BA0
181
6.7 Testing the PLC program
6.7.1 Startup characteristics
Startup of a SIMATIC-CPU module can be set for the following startup modes:
● Restart
● Cold restart (Warm restart)
● Cold restart
In case of a SINUMERIK 840Di sl the startup type of the PLC is set permanently to NEW
START. It cannot be changed.
Startup mode: RESTART
Upon NEW START first the block "OB 100" is executed. Then cyclic operation starts with
call-up of block "OB1".
The following data are kept in the case of COLD RESTART:
● All data blocks and their contents
● Retentive timers, counters and flags
Retentive ranges
The ranges of the times, counters and markers, which are to be retentive, must be set via
the dialog Properties, tab Retention of the PLC-CPU-module.
NOTICE
The retention of the data areas can only be achieved with the backup supply (backup
battery) active. If the battery backup is empty, the PLC will not restart.
The following operations are performed during a restart:
● UStack, BStack and non-retentive flags, timers and counters will be deleted
● The process output image (POI) will be deleted
● Process and diagnostics alarms will be canceled
● The system status list will be updated
● Parameterization objects of modules (from SD100 onwards) will be evaluated or defaults
parameters will be output to all modules in single-processor mode
● OB100 (cold restart) is executed
● The process input image (PII) is read in
● The command output disable (COD) is canceled
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