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7.5 Integration of organization blocks (OBs)
If the SIEMENS SIMATIC S7 automation system is used, a number of so-called
"organization blocks" are available for the operator.
Organization blocks are the interface between the operating system of the CPU and
the user program. OBs are used to execute specific program sections, e.g. if errors
are present or in case of process alarms.
Organization blocks are executed according to the priority they are allocated.
Basically, if the corresponding OB is not included, in case of an error the Controller-
CPU changes to the
STOP
mode. If this behavior is not desired the corresponding OB
must be implemented. In addition the OB must not have been programmed explicitly.
Only if a special error response is desired, the OB must be programmed accordingly.
A call of OBs is performed if the position of the measuring system is accessed during
a system failure.
Details on organization blocks see SIEMENS documentation
6ES7810-4CA08-8BW1,
“System Software for S7-300/400 System and Standard
Functions Volume 1/2”
With respect to the measuring system relevant organization blocks are listed
followingly.
7.5.1 Diagnostic alarm OB (OB 82)
Generally, this OB is triggered if the measuring system transmits a diagnostic alarm to
the controller, see chapter
“PROFINET Diagnostic alarm” on page 89.
7.5.2 Insert / remove module OB (OB 83)
Generally, this OB is triggered if the data status is changing from
BAD
to
GOOD
. In this
case a so-called
Return-of-Submodule-Alarm
is transmitted by the measuring
system to the controller, also see chapter
“Data status” on page 87 and “Return of
7.5.3 Priority class error OB (OB 85)
Generally, this OB is triggered if the data status is changing from
GOOD
to
BAD
, see
chapter
