Technical data

Table Of Contents
Organization Blocks
System Software for S7-300/400 System and Standard Functions - Volume 1/2
1-32
A5E00709327-01
1.17 Power Supply Error Organization Block (OB81)
Description
The operating system of the S7-300 CPU calls OB81 whenever an event occurs
that is triggered by an error or fault related to the power supply (only on an S7-400)
or the back-up battery (when entering and when outgoing event).
In S7-400, OB81 is only called in the event of a battery fault if the battery test
function has been activated with the BATT.INDIC switch.
The CPU does not change to the STOP mode if OB81 is not programmed.
You can disable or delay and re-enable the power supply error OB using SFCs 39
to 42.
Local Data for the Power Supply Error OB
The following table describes the temporary (TEMP) variables for the power supply
error OB. The variable names are the default names of OB81.
Variable Type Description
OB81_EV_CLASS BYTE Event class and identifiers:
B#16#38: outgoing event
B#16#39: incoming event
OB81_FLT_ID BYTE Error code: (possible values)
B#16#21, B#16#22, B#16#23, B#16#25, B#16#26,
B#16#27, B#16#31, B#16#32, B#16#33)
OB81_PRIORITY BYTE Priority class; can be assigned via STEP 7 (hardware
configuration)
For example, possible values for the RUN mode: 2-26
OB81_OB_NUMBR BYTE OB number (81)
OB81_RESERVED_1 BYTE Reserved
OB81_RESERVED_2 BYTE Reserved
OB81_RACK_CPU WORD Bits 0 to 7: B#16#00
Bits 8 to 15:
- For a standard CPU: B#16#00
- For a H-CPU: Bits 8 to 10: Rack no., Bit 11:
0=Reserve CPU, 1=Master CPU,
Bits 12 bis 15: 1111
OB81_RESERVED_3 BYTE Relevant only for error codes B#16#31, B#16#32 and
B#16#33
OB81_RESERVED_4 BYTE Relevant only for error codes B#16#31, B#16#32 and
B#16#33
OB81_RESERVED_5 BYTE Relevant only for error codes B#16#31, B#16#32 and
B#16#33
OB81_RESERVED_6 BYTE Relevant only for error codes B#16#31, B#16#32 and
B#16#33
OB81_DATE_TIME DATE_AND_TIME DATE_AND_TIME of day when the OB was called