S7 Array Index

S7PP · Mar 29, 2011

Hi guys, how are you doing?

Quick question about array: if I want to use an array of INT in step 7 with an index, how should I define "index"? DWord or INT or DINT? and how to write it in program?

L Array[index]
T MW20

I'm using STL don't have SCL yet.

TurpoUrpo · Mar 29, 2011

Not possible in stl. Just in SCL. STL (and LAD/FBD) supports only fixed array indexes.

S7PP · Mar 29, 2011

Really?

That's too bad.

Thanks anyway.

L D[AR2P#0.0] · Mar 29, 2011

You can write an FC to perform array accesses though.
Should the aray index be zero based ?

Simple example below:

S7PP · Mar 29, 2011

I got what you mean. That's clever.

I was trying to do:

L 9
T #aTest[#index] instead of #aTest[1]

in FB1.

Thanks

denhondt · Apr 17, 2011

Code:

 L     P##pArrayOfInts
      LAR1  
      L     W [AR1,P#0.0]
      T     #wDB
      L     D [AR1,P#2.0]
      LAR1  
      L     #iArrayIndex
      SLD   4
      +AR1  
      OPN   DB [#wDB]
      L     W [AR1,P#0.0]
      T     #RET_VAL
      SET   
      SAVE

I don't understand this part of it

L W [AR1,P#0.0] (Why this is saved in wDB???)
T #wDB

L D [AR1,P#2.0] (DW2.0 Contains the value 9 ???)
LAR1

L D[AR2P#0.0] · Apr 17, 2011

All parameters to FC's are passed as 32bit area pointers.

The array is passed as a pointer parameter in FC1. A pointer parameter contains the DB number (16bits)and the area pointer(32 bits) and hence cannot be passed directly to the FC. The editor generates code that copies the DB number and the area pointer into the temp area of FB1 and then passes a pointer to this area when calling FC1. See commented monitored code:

denhondt · Apr 17, 2011

This loads P##DB1.DBX0.0 in AR1(Adresregister 1)
L P##pArrayOfInt
LAR1

AR1 =Adresregister 1 =/= Local area?

AR1 contains P##DB1.DBX0.0

I thought that this would load the content of DB1.DBW0
L W [AR1,P#0.0]
T wDB

And this i tought would load the content of DB1.DBD2 (dw2= 9 )
L D [AR1,P#2.0]
LAR1

L D[AR2P#0.0] · Apr 17, 2011

denhondt said:
This loads P##DB1.DBX0.0 in AR1(Adresregister 1)
L P##pArrayOfInt
LAR1

No it does not. An address register contains an area pointer, it does not contain the DB number.

The monitored code clearly shows AR1 contains 87000038H (V7.0)
The V area is the L area of the preceding block i.e. V7.0 in FC1 is the same as L7.0 in FB1

denhondt · Apr 17, 2011

Thanks for the answer,
Nowi understand it.

sarana.automation · Apr 13, 2012

thanks LD [AR2,P#0.0] and all of you
i found your block (FC1) usefully to me

regards,
sarana.automation

S7 Array Index

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L D[AR2P#0.0]

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