DO Instruction Conversion with DBs

Hello All,

I have been looking for some knowledge base on S5 DO instruction.  I have been able to figure out the indirect addressing when it comes into play for DW/FWs.  I have just come across 'DO DB 148'.  Below i have included the JU and then the logic inside.

JU FB 48

NAME: MULW

IN:  DW 100

INDB:  DB 148

MUL:  KG +25.4000015

OUT:  DW 100

OUTD:  DB 149

FB 48 LOGIC

DO  =INDB

L  =IN

JU  OB 220

FDG

LWD  =MUL

XG

GFD

DO  =OUTD

T  =OUT

DB 148 and DB 149 have lengths of 254.  Any/all assistance with this would be great. 

Thank you in advance!

fritz,

Thank you for your response - that helped us tremendously.  We have only a few blocks remaining and have come across another type of instance of a "DO" operation.  I am unclear if it actually is an operation or some dead code that was left in from the original programmer (20 years ago).  Please see below: 

DO  FW 208

A     F  0.0

DO  =TWDB

DO  FW 214

L      DW 0

SD   =TWA

So from the context of what I have figured out before and what you so graciously assisted with, I can decipher most of the above network.  Basically, it is calling a DB (=TWDB) and the loading the timer preset value DW (FW 214) and then starting the on-delay timer.  

I do not know what that first DO FW 208 is doing though if anything.  Can you indirect address F 0.0 with the value in FW 208?  Or is that just something that was left there?

Thanks

Hey RPalanzo,

You are correct above, and it does the same  indirect addressing for the Flag bit which start the timer

  A  F [FW208]

   SD Timer

When indexing binary operations, indicate the bit address in the high byte of this word and the byte in the lower byte of FW

Ex: FW208 = _KH0108    then   

  A    F 8.1

  SD   T  1

Has been a long time don't have to deal with S5, but I thing I got it right

Marciano