Rockwell Automation PLC-5 Fieldbus Solutions for Integrated Architecture User Manual - Manual (Page 21)

Publication 1757-UM006A-EN-P - May 2002
The Fieldbus Communication Model 1-7
Function blocks make it possible to build a control loop using fieldbus
devices that include the appropriate Function block types. For
example, a pressure transmitter that contains an Analog Input and
Proportional/Integral/Derivative blocks can be used with a valve
containing an Analog Output block to form a control loop, as shown
in Figure 1.3.
Figure 1.3 Using Function Blocks in Fieldbus Devices to Form a Control Loop
Fieldbus
AI Block
PID Block
AO Block
Device 1
Device 2