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Array Indexing

Created by: lgray66 at: 12/16/2011 5:57 PM (9 Replies)

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12/16/2011 5:57 PM	Rate (0)
lgray66 Regular Member Joined: 8/9/2011 Last visit: 9/27/2024 Posts: 19 Rating: (0)	Hello, I cannot get Step 7 Professional V11 to accept the use of a variable for an array index. The help page shows the following: "<Data block>".<ARRAY>["i"] // one-dimensional ARRAY Here is mine: "Zone Variables".Setpoint_F["Zone Graph Index"] where "i" and "Zone Graph Index" is index the variable of type int. I've tried it with and without the " ", and I've tried a local Temp variable. The error is "The entered index is invalid". I'm using an S7-300 (CPU 315-2 PN/DP). What am I doing wrong? Thanks, Larry

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12/16/2011 6:32 PM	Rate (0)
Marko Bursic Platinum Member Joined: 9/8/2009 Last visit: 7/17/2023 Posts: 1410 Rating: (153)	What language do you use LAD,FBD,STL,SCL? You can do arrays with index addressing only in SCL, this is my opinion, wait for some expert to respond. You can do your program in STL with indirect addresing with use of address registers AR1 and AR2, search on forum and you will find some example, you can also write a pseudo code program of your problem, so we can help you. Also give explanation about your datablock, is it shared datablock or you will compute this in FB with data stored in instance DB.

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12/16/2011 7:21 PM	Rate (0)
lgray66 Regular Member Joined: 8/9/2011 Last visit: 9/27/2024 Posts: 19 Rating: (0)	Hello, Thanks for the reply. I'm using ladder programming. The DB is global. There is an example of using LAD in the help file: The following example shows the indirect indexing of an ARRAY component as an example of LAD. ARRAY is a three-dimensional ARRAY. "Tag_1", "Tag_2" and "Tag_3" are PLC tags of the "Integer" data type. Depending on their values, one of the ARRAY components will be copied to the "MyTarget" tag. Thanks, Larry Attachment Index Error.JPG (3144 Downloads)

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12/16/2011 8:04 PM	Rate (0)
Marko Bursic Platinum Member Joined: 9/8/2009 Last visit: 7/17/2023 Posts: 1410 Rating: (153)	OK, I understand that you're not able to use indexes in LAD, because is not possible. I don't undrestand what about that example of three dimensional array, where you found it and can you make a screenshot?

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12/16/2011 8:44 PM	Rate (0)
lgray66 Regular Member Joined: 8/9/2011 Last visit: 9/27/2024 Posts: 19 Rating: (0)	Hello, Thanks for your help, I've came to the same conclusion, this is not possible with LAD. I was able to do it in SCL, as you suggested. I've attached the screen shot from the help system, that shows it is possible. This is the standard help file that comes with v11. Maybe they are going to add it in SP2, and the help file is ahead of Step 7? Thanks, Larry Attachment Index Help.JPG (4076 Downloads)

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12/17/2011 11:26 AM	Rate (0)
Marko Bursic Platinum Member Joined: 9/8/2009 Last visit: 7/17/2023 Posts: 1410 Rating: (153)	Yes, you are right I have found it in new manual (SP2), this is something realy new.

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1/29/2018 9:09 PM	Rate (0)
jtodora Posts: 1 Rating: (0)	I'm new to Siemens and what I'm about to say might not be accurate. I too have been trying to dynamically index an array in S7-300 using the CPU315-2 PN/DP and found that it is not possible in LAD. I'm using TIA Portal v14 and the help files do not show any ladder examples, only SCL. Array indexing in LAD works great in the S7-1200's, so maybe the LAD image was showing an example for the S7-1200/S7-1500?
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1/29/2018 9:45 PM	Rate (0)
#dP Posts: 2826 Rating: (688)	Hello jtodora I'm new to Siemens and what I'm about to say might not be accurate. I too have been trying to dynamically index an array in S7-300 using the CPU315-2 PN/DP and found that it is not possible in LAD. I'm using TIA Portal v14 and the help files do not show any ladder examples, only SCL. Array indexing in LAD works great in the S7-1200's, so maybe the LAD image was showing an example for the S7-1200/S7-1500? You are correct: The S7-300 and S7-400 does not have array index referencing in LAD and FBD as with the S7-1200 and S7-1500. It has nothing to do with the software.\ Try using SCL. BR
#dP Posts: 2826 Rating: (688)
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1/30/2018 8:05 AM	Rate (0)
IBN-Service Posts: 8946 Rating: (999)	lgray66 ... "<Data block>".<ARRAY>["i"] // one-dimensional ARRAY .. Like dP already said: use SCL.
IBN-Service Posts: 8946 Rating: (999)
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This contribution was helpful to 3 thankful Users #dP 0_Einstein edo017

4/10/2021 12:09 AM	Rate (0)
AutoGen_6239819 Member Joined: 11/7/2019 Last visit: 1/8/2025 Posts: 1 Rating: (0)	When I made the data type of my index parameter type int (integer) then it worked for me. Using TIA Portal V15.1 and S7-1500 processor.

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