ABB Advant Controller 450 - Execution Sequence for an Individual PC Element

Advant
®
Controller 450 User’s Guide
Chapter 4 Runtime Operation
4-24 3BSE 002 415R701 Rev A
4.1.10.4 Execution Sequence for an Individual PC Element
The execution sequence within a PC element is illustrated in Figure 4-16 by an AND-gate with
two inputs.
The order of execution is:
• The interpreter reads function type, in this case AND, and selects the program code for the
function AND from the element library.
• Current values at the storage places pointed out by inputs 1 and 2 are read and the logical
AND-condition is formed with the help of the program code AND.
• The result is stored at the storage place specified for output 20.
The interpreter then resumes control and searches for the next PC element to be executed.
Figure 4-16. Order of Execution for PC Elements, AND Gate with two Inputs
&
1
2
20
Memory map
The
AND function
Address to data
for input 1
Address to data
Address to data
for input 2
for output 20