S5-115F Manual
Rules Governing the Use of the S5-115F
Increases in PLC scan time
If you call FB 255 DEPA, the PLC scan time increases as follows:
•
110 ms, if a digital input of I/O type 3 was the cause of passivation,
•
140 ms, if a digital input of I/O type 10 was the cause of passivation
•
30 ms, if an analog input of I/O type 14 or 15 was the cause of passivation.
Interrupt processing
If you have configured an interrupt response time of less than 30 ms when initializing the
operating system with COM 115F, the interrupt response will increase to 30 ms during processing
of FB 255 DEPA.
For safety reasons, you must switch off the load voltage of the I/O modules before expiry of the
second error occurrence time. You can avoid having to switch off here if you depassivate the I/O
modules before expiry of the second error occurrence time.
Example: Depassivation of I/O modules
A boiler is heated by four burners. The burners work independently of each other so that each
burner control constitutes an autonomous subprocess. Signal groups 11 to 14 are assigned for the
I/O modules of these subprocesses.
The entire control is monitored by a pre-interlock. Since the pre-interlock applies to all four
burners and is of primary safety significance, signal group 0 is assigned to the I/O modules.
Figure 10-39. Dividing the I/O Modules into Signal Groups
Pre-Interlock of Burner Control
I/O modules for pre-interlock with signal group 0
Burner 1
I/O modules with
signal group 11
Burner 4
I/O modules with
signal group 14
Burner 3
I/O modules with
signal group 13
Burner 2
I/O modules with
signal group 12
EWA 4NEB 811 6148-02
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