Operating Modes; Startup Mode - Siemens SIMATIC S7-1500/ET 200MP System Manual

Commissioning

12.5 Operating modes

12.5 Operating modes
Introduction
Operating states describe the behavior of the CPU at a specific time. The following operating
states are possible via the mode selector:
• STARTUP
• RUN
• STOP
In these operating modes, the CPU can communicate, for example, via the PROFINET IO
interface (X1).
The status LEDs on the front side of the CPU indicate the current operating mode.
12.5.1

STARTUP mode

Response
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.
Points to note
• 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.
To read the current state of inputs during STARTUP, you can access inputs with direct I/O
access.
To initialize outputs during STARTUP, you can write values via the process image or with
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.
264
Automation system
System Manual, 01/2023, A5E03461182-AK