Commissioning
8.4 Operating modes
S7-1500 Automation System
System Manual, 01/2013, A5E03461182-01
103
8.4.2 "STARTUP" mode
Function
Before the CPU starts to execute the cyclic user program, a startup program is executed.
By suitably programming startup OBs, you can specify initialization tags for your cyclic
program in the startup program. That is, you can set up one or several startup OBs in your
program, or none at all.
Special features during startup
Note the following points regarding the "STARTUP" mode:
● All outputs are disabled or react according to the parameter settings for the respective
module: They provide a substitute value as set in the parameters or retain the last value
output and bring the controlled process to a safe operating mode.
● The process image is initialized.
● The process image is not updated.
In order to read the current state of inputs during STARTUP, you can access inputs by
direct I/O access.
In order to initialize outputs during STARTUP, values can be written via the process
image or via direct I/O access. The values are output at the outputs during the transition
to the RUN mode.
● The CPU always starts up in a warm restart.
– The non-retentive bit memories, timers and counters are initialized.
– The non-retentive tags in data blocks are initialized.
● During startup, no cycle time monitoring is running yet
● The startup OB are executed in the sequence of the startup OB numbers. All startup OBs
that you have programmed are executed, regardless of the selected startup mode.
● The following OBs can be started during startup, if a corresponding event occurs:
– OB 82: Diagnostic error interrupt
– OB 83: Removal/insertion of modules
– OB 86: Rack error
– OB 121: Programming error (only for global error handling)
– OB 122: I/O access error (only for global error handling)
All other OBs cannot be started until the transition into the "RUN" operating mode.
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