Indirect Addressing Advanced Exercise from PLCDEV.com

Test Code

Hello LD,

I tested your code and found out result acc to question .But some parts in your code i do confusion. Could you give me a hand to understand in this code or explain a bit?

1.
L 2 // first ACCU1 then move to ACCU2
FL: T #ii // fetch array index

Why we need to intialize array index with 2 and later subtract 1 to get DB index 1?

2.
L #ii // fetch array data
+ -1 //

Result will store in ACCU1?

SLD 5 // shift 5 for DWORD and REAL in S7
LAR1 P#DBX 0.0 //

load AR1 with pointer + "above result" ACCU1?

Can i monitor ACCU1 online? i only found ACCU2 to monitor.
Thanks in advance and please!

Re: Your question 1

The fact that you have asked this question implies you have not read and comprehended posts 10,11,12,13
Go back to them and follow the steps I took in hand compiling the pseudo code. Do not move on to the next step until you understand each one.

Re: Your qeustion 2

Click on the instruction and then press F1 and read the Siemens Help.

Re: Your Question 3

Accu1 is titled (confusingly) Standard and is enabled by right clicking in the right hand side of the screen and selecting default status.

correct for zero based addressing in STL

L D[AR2 said:

Finally, add in the Begin..End processing.

Code:

      L     2
FL:   T     #ii
      L     10
      >I    
      JC    endf

//Let x:=Values[i]  for convenience
      OPN   "PreFill Values"            //open value db
      L     #ii                         //fetch array index 
      +     -1                          //correct for zero based addressing

Click to expand...

Hello LD,

Could u please explain me why u have "Correct for zero based addressing by adding +1? Coz my array is start from [1..10] ? Code is working but i wanted to understand more about your comments such as "correct for zero based addressing" and "for convenience".

After i read it, your post #17 and read it again ur post, i got it ald. Thanks again LD.