Siemens S7/TIA v18: What's the order of execution here?...

[Mas01]

Another daft question coming up...

In the picture, suppose "Data_block_1.Calculate Diff" is TRUE.

What's the order of execution of the SUBtraction blocks? Is it 1, 2, 3 or are they done simultaneously?
Thanks

 

[parky]

It is normal for code to be processed left to right top to bottom so yes that is correct, however, when there are other contacts in "OR" configuration before those functions then these are processed first.
for example
as the raw code is processed if for example you had another N/O contact ored across that one it would process in the following maneer
Siemens uses brackets for multiple lines for grouping just like in maths where Mitsubishi use things like AB ORB & some others I cannot remember (only shown in STL)
A(
O Mxxx
O Mxxx
)
SUB xxx (1)
SUB xxx (2)
SUB xxx (3)

 

[mk42]

Definitely not simultaneously. The PLC is definitely single threaded (although the newest 1500s have a 2nd core for comms).


It should execute in order 1,2,3

 

[Mas01]

Thanks for the replies, really appreciate it.
Yes I should've specified the PLC , it's S7-1200 with a 1212C CPU. Cheers