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Old January 15th, 2022, 12:53 PM   #1
Hal9000
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Tia Portal Pro - Word Array to Real Struct?

Hi there,

I have an array of 44 words that contain the two parts of a set of real numbers. I want to copy these words over to my Struct which contains the 22 Reals.

I've tried all the obvious Block Move type instruction options in TIA portal but non of them seem to work for me.

Can anyone suggest away to do this?

The image should make things clearer.

Many thanks,

Justin
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File Type: jpg Word to Real.jpg (218.0 KB, 64 views)
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Old January 15th, 2022, 01:02 PM   #2
drbitboy
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What are the correct values for some of the REALs, and the corresponding values for the WORDs? Doesn't have to be exact, if the numbers are fluctuating.


Offhand, the REAL values being negative suggests the order of the words and/or of the bytes are reversed. Try swapping every other word before the block move, then try swapping bytes within the words. There are only so many possibilities.
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Old January 15th, 2022, 03:35 PM   #3
L D[AR2,P#0.0]
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Example code to swap the modbus words to give different flooting point results. As already said, what should the data be?
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Old January 15th, 2022, 03:37 PM   #4
Lare
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https://support.industry.siemens.com.../view/42603881


Example 2 is for copying between different types, but do you need also word -> real conversion between?
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Old January 15th, 2022, 03:37 PM   #5
L D[AR2,P#0.0]
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db contents:
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Old January 16th, 2022, 12:45 AM   #6
drbitboy
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@LD and @Lare have it:

Python:

>>> import struct

>>> struct.unpack('>5f',struct.pack('>10H' ,0x4280,0x4fcb ,0x420d,0x6776 ,0x4213,0xa2e8, 0x0000,0x0000, 0xc087,0x80ea))
(64.15584564208984, 35.351036071777344, 36.909088134765625, 0.0, -4.2344865798950195)

>>> [hex(v) for v in struct.unpack('>5I',struct.pack('>10H' ,0x4280,0x4fcb ,0x420d,0x6776 ,0x4213,0xa2e8, 0x0000,0x0000, 0xc087,0x80ea))]
['0x42804fcb', '0x420d6776', '0x4213a2e8', '0x0', '0xc08780ea']


I have no idea where OP is getting the data for their floating point values in [AlgInput], it is almost certainly not from the Words in [InputRegister]

>>> [hex(v) for v in struct.unpack('>4I',struct.pack('>4f',-689.4691,-5573.278,-252997.5,-9999.9))]
['0xc42c5e06', '0xc5ae2a39', '0xc8771160', '0xc61c3f9a']


There may be an issue with how the data are physically laid out in the Struct with the 22 reals. Isn't there an "optimized" option for data blocks?
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Old January 16th, 2022, 06:27 AM   #7
mad4x4
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Quote:
Originally Posted by Hal9000 View Post
Hi there,

I have an array of 44 words that contain the two parts of a set of real numbers. I want to copy these words over to my Struct which contains the 22 Reals.

I've tried all the obvious Block Move type instruction options in TIA portal but non of them seem to work for me.

Can anyone suggest away to do this?

The image should make things clearer.

Many thanks,

Justin
You should be able to set up a function to do it, I found this coded on another forum and it is similar to how I used to do it on Allen Bradley. I assume these are Modbus registers coming in, only problem might be the big endian / little endian fromat ( BCDA v CBAD)

If those 2 words contain floating point number formatted as IEEE 754, then proceed as follows:

Code:
L FirstModbusWord

T MW20

L SecondModbusWord

T MW22

...

L MD20
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Old January 16th, 2022, 07:52 AM   #8
Hal9000
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Hi everyone,

Please ignore the actual data in the reals. It's old data not any data that was copied across. Sorry for confusion.

I basically just need to understand what instruction will allow me to move the data from one data type to another. Being words in an array to Reals in a struct. the start address and count of the array I need to be able to adjust. The destination structs will of course be fixed.

I will have a look at the Siemens link Lare provided,

Many thanks
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Old January 16th, 2022, 08:06 AM   #9
L D[AR2,P#0.0]
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If you have to swap the words, there is no instruction to do this whilst performing a block move or the like. You will have to create in intermediate array as in my example - you can then block move the swapped array to your struct of reals.
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Old January 16th, 2022, 11:22 AM   #10
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Quote:
Originally Posted by L D[AR2,P#0.0] View Post
If you have to swap the words, there is no instruction to do this whilst performing a block move or the like. You will have to create in intermediate array as in my example - you can then block move the swapped array to your struct of reals.

Swap command should work also for P area if data is words or dwords.



Haven't tested how it works if serialize blocks outputs is word area, then swap for entire structure and after that deserialize.


At least it should work if first moving from bytes to words and after that swap.
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Old January 16th, 2022, 04:14 PM   #11
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Even though you did not supply the actual values, I am pretty sure that @LD nailed it on the values:
  • It appears the Modbus receive buffer and S7-1200 Reals are both MSB-first, so a swap is not necessary
  • A range of 35-65 is reasonable for pressures and temperatures in any system of units.
The image below shows a minimal implementation of Example 2 from the link that @Lare supplied, for the first five pairs of words from the OP; OP will of course have to provide their own size for the [store] array in the "COP" FC.

xxx.png
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Last edited by drbitboy; January 16th, 2022 at 04:18 PM.
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Old January 16th, 2022, 04:25 PM   #12
drbitboy
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P.S. I did uncheck [Optimized block access] for the block containing the Struct with the Reals, but that may not be necessary.

yyy.png
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ii) There is no software problem that cannot be solved with another layer of indirection.
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Old January 16th, 2022, 05:56 PM   #13
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Quote:
Originally Posted by drbitboy View Post
Even though you did not supply the actual values, I am pretty sure that @LD nailed it on the values:
  • It appears the Modbus receive buffer and S7-1200 Reals are both MSB-first, so a swap is not necessary
  • A range of 35-65 is reasonable for pressures and temperatures in any system of units.
The image below shows a minimal implementation of Example 2 from the link that @Lare supplied, for the first five pairs of words from the OP; OP will of course have to provide their own size for the [store] array in the "COP" FC.

Attachment 60683

I maybe would use temp bytes with lenght of 0..249 bytes. That way it would work to all modbus query lenghts, lenght 255 for sure.
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