Introduction to STEP 5 S5-115F Manual
The length of the OBs is calculated as follows:
Operation code max. 127 words
+ Header 5 words
+ BE operation 1 word
If the block is longer than 127 words (operation code), a BLD 255 operation with a program
counter sequence will result at the latest in the 128th codeword. Interposed BLD segmentation
operations are unaffected by this.
The following OBs are provided by the CPU 942F:
Table 2-3. Overview of Organization Blocks
OB must be user-programmed and is called by the operating system.
OB 1 Cyclic program scanning
Interrupt-driven program scanning
Process interrupt A: Interrupt generation by the 434 digital input moduleOB 2
Time interrupt: ( variable in each case: 100 msec. to 10 min. 55 sec. )
OB 21 Manual power-up
OB 22 Automatic power-up when power is restored
Handling of restart procedures
OB 251 PID control algorithm
1
OB is already programmed. OB must be called by the user.
OB 13
OB No. Function
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1 This block does not appear in the ”DIR PLC” display on the programmer.
2-8
EWA 4NEB 811 6149-02