# How to read Real Value on Modbus for codesys v3.5

**URL:** https://www.wago.community/t/how-to-read-real-value-on-modbus-for-codesys-v3-5/551
**Category:** CODESYS
**Tags:** codesys, cc100
**Created:** [July 26, 2023, 10:19am UTC](https://www.wago.community/t/how-to-read-real-value-on-modbus-for-codesys-v3-5/551 "2023-07-26T10:19:20Z")
**Posts on this page:** 8
**Page:** 1

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### Author: ![hkn\_blt](https://avatars.discourse-cdn.com/v4/letter/h/9f8e36/32.png) [@hkn\_blt](https://www.wago.community/u/hkn_blt)
#### Post date: [July 26, 2023, 10:19am UTC](https://www.wago.community/t/how-to-read-real-value-on-modbus-for-codesys-v3-5/551/1 "2023-07-26T10:19:20Z")

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Hello!  
I have a device that I communicate with modbus tcp. The data it sent me is of real type. How should I read this data in codesys by converting?  
Data is read word by word in codesys 3.5

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### Author: ![bjornidar](https://avatars.discourse-cdn.com/v4/letter/b/5fc32e/32.png) [@bjornidar](https://www.wago.community/u/bjornidar)
#### Post date: [July 28, 2023, 12:18pm UTC](https://www.wago.community/t/how-to-read-real-value-on-modbus-for-codesys-v3-5/551/2 "2023-07-28T12:18:49Z")

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1. Create a DUT og type UNION with a Word array of size 2 and a REAL value.
2. Copy the two modbus words (per real value) into the unions array.
3. Read the REAL value out of the UNION directly.

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### Author: ![WagoMark](https://avatars.discourse-cdn.com/v4/letter/w/d07c76/32.png) [@WagoMark](https://www.wago.community/u/WagoMark)
#### Post date: [July 28, 2023, 2:10pm UTC](https://www.wago.community/t/how-to-read-real-value-on-modbus-for-codesys-v3-5/551/3 "2023-07-28T14:10:00Z")

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![image](https://us1.discourse-cdn.com/flex016/uploads/wago/original/1X/ae9a2848e1775ff2832cfff0754c0acfb15d32fb.png)

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### Author: ![hkn\_blt](https://avatars.discourse-cdn.com/v4/letter/h/9f8e36/32.png) [@hkn\_blt](https://www.wago.community/u/hkn_blt)
#### Post date: [July 29, 2023, 1:20pm UTC](https://www.wago.community/t/how-to-read-real-value-on-modbus-for-codesys-v3-5/551/4 "2023-07-29T13:20:22Z")

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Why you use pointer ?

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<div class="post-metadata">

### Author: ![WagoKurt](https://sea2.discourse-cdn.com/flex016/user_avatar/www.wago.community/wagokurt/32/11_2.png) [@WagoKurt](https://www.wago.community/u/WagoKurt)
#### Post date: [July 31, 2023, 9:24pm UTC](https://www.wago.community/t/how-to-read-real-value-on-modbus-for-codesys-v3-5/551/5 "2023-07-31T21:24:43Z")

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Another approach that uses overlapped memory, using the compiler to convert between WORD and REAL. Tip: make sure that the REAL is on an even byte boundary in the server.

```auto
VAR
   myWORD_LowByte AT %MW0 : WORD;
   myWORD_HighByte AT %MW1 : WORD; 
   myREAL AT %MW0 : REAL;
END_VAR
 
myWORD_LowByte := ModbusArray[0];
myWORD_HIghByte := ModbusArray[1];
myReal; // This will be the REAL Value

```

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<div class="post-metadata">

### Author: ![hkn\_blt](https://avatars.discourse-cdn.com/v4/letter/h/9f8e36/32.png) [@hkn\_blt](https://www.wago.community/u/hkn_blt)
#### Post date: [August 1, 2023, 5:19am UTC](https://www.wago.community/t/how-to-read-real-value-on-modbus-for-codesys-v3-5/551/6 "2023-08-01T05:19:16Z")

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I want to ask one more thing. What should I do when the incoming data is big endian or little endian?

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### Author: ![WagoKurt](https://sea2.discourse-cdn.com/flex016/user_avatar/www.wago.community/wagokurt/32/11_2.png) [@WagoKurt](https://www.wago.community/u/WagoKurt)
#### Post date: [August 3, 2023, 7:36pm UTC](https://www.wago.community/t/how-to-read-real-value-on-modbus-for-codesys-v3-5/551/7 "2023-08-03T19:36:59Z")

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You can map it to the byte level with the same approach, and change the mapping as needed.

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### Author: ![CpGelot](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@CpGelot](https://www.wago.community/u/CpGelot)
#### Post date: [April 26, 2024, 11:08am UTC](https://www.wago.community/t/how-to-read-real-value-on-modbus-for-codesys-v3-5/551/8 "2024-04-26T11:08:21Z")

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![image](https://us1.discourse-cdn.com/flex016/uploads/wago/original/1X/bac104abe84ee57a42a39f102f403a33b44cd623.jpeg)

Pl. check the different methods