Indirect addressing in converting s5 to s7 - What if DB is not called in the program?

Hi experts,

about indirect addressing in converting s5 to s7, what if DB is not called in the program? what is the use of instruction "B" ?
here is some part for the sample  of s5 program

L KH 000F

T DW 34

L KF +3

T DW36

INI: B DW34

U M0.0

SPB =M1

SPA=INC

M1: B DW36

L DW0

L DW32

-F

T DW92

SPB=PAS2

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Split from What is the B instruction ???.

 The answer is just two posts above your question.

fritz

Hello Yann_GPC

the "B" instruction is used for indirect addresing ("B" is the German mnemonic, "DO" isthe English mnemonic).
Put simple, the command following the "B" (or"DO") instruction is executed based on the variable value of the "B" instruction, for example:
L KF +41

A DB 110 // open DB 110

T DW 220 // store 41 in DW 220

B DW 220 // next instruction will use the value that's in DW220

L DW 0 // = L DW 41 from DB 110

Your example logic does not show the end of what's presumably a loop, but seemsall up to do a simplecopying ofa bunch of variables from DB110 as of DW41 to DB120 as of DW102.
One possible replacement for this is SFC20 "BLKMOV", but if you prefer to manually re-program it you'll find the FAQ What is the difference between STEP 7 and STEP 5 with regard to the operations for indirect addressing? helpful.

I hope this helps