Introduction to Industrial Automation

Figure 7.6  Two different POUs (FB10 and FB11) call the same FC100.

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  Introduction to Industrial Automation

With the introduction and utilization of the above POUs in a large industrial system, the 

automation program can get a structure that will fit with the distributed nature of the industrial 

processes. In general, the industrial processes are not concentrated in a specific place; rather, they 

consist of individual sections with a different task and geographical placement each. Figure 7.7 

presents the structure of an automation program consisting of multiple POUs, such as OB, FB, 

and FC, which can perfectly correspond to the operation of the individual parts of an industrial 

process. The complexity of a program does not depend on a large number of different FBs, but the 

DB4

DB3

DB1

CALL  FB1

CALL  FB2

CALL  FC3

CALL  FB3

FB1

CALL FC1

FC1

DB2

FB2

CALL FC2

CALL FC2

FC2

FC3

CALL FC4

FC4

OB1

Other Instruction

s

Other Instruction

s

FB3

CALL FB4

FB4

DB4

DB3

DB1

CALL  FB1

CALL  FB2

CALL  FC3

CALL  FB3

FB1

CALL FC1

FC1

DB2

FB2

CALL FC2

CALL FC2

FC2

FC3

CALL FC4

FC4

OB1

Other instructions

Other instructions

FB3

CALL FB4

FB4