# Convert Modbus temperature value

**URL:** <https://forum.inductiveautomation.com/t/convert-modbus-temperature-value/7523>\
**Category:** Ignition\
**Created:** [November 6, 2013, 4:05am UTC](https://forum.inductiveautomation.com/t/convert-modbus-temperature-value/7523 "2013-11-06T04:05:11Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![getabc](https://avatars.discourse-cdn.com/v4/letter/g/278dde/32.png) [@getabc](https://forum.inductiveautomation.com/u/getabc)\
**Post date:** [November 6, 2013, 4:05am UTC](https://forum.inductiveautomation.com/t/convert-modbus-temperature-value/7523/1 "2013-11-06T04:05:11Z")

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Hello Team,

I’m fairly new to IA, so forgive my ignorance.

![](https://us1.discourse-cdn.com/inductiveautomation/original/3X/2/f/2f0984456f8dd47c5beb0a68b72c3d6cf62ef2aa.jpeg)

The current modbus value returns 14520 and according to the manual I need to convert it with (Value/100 – 70). So, what are my options in doing so?

Secondly, the converted value is in Fahrenheit, so how to convert it to Celsius?

Thanks,

Andrew

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**Author:** ![JordanCClark](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/jordancclark/32/83362_2.png) [@JordanCClark](https://forum.inductiveautomation.com/u/JordanCClark)\
**Post date:** [November 6, 2013, 11:49am UTC](https://forum.inductiveautomation.com/t/convert-modbus-temperature-value/7523/2 "2013-11-06T11:49:04Z")

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Here are a couple of options.

[ul] Option 1: Use two tags.  
[list]One OPC Tag to read the raw value, one Expression Tag to do the math. The second tag will use an expression like:code\*5/9[/code] This will give your final value in degrees Celsius.[/ul]

Option 2: Use Scaling properties in your OPC tag.  
[ul]Since we now have a handy formula, plug in full deflection values (for a 16-bit number, that would be 0 and 65535) to get values of -56.67 and 307.42 that you can plug into the scaling properties. This is found in the Numeric section of the dialog box.[attachment=0]11-6-2013 6-44-01 AM.png[/attachment][/ul][/list:u]

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<div class="post-metadata">

**Author:** ![getabc](https://avatars.discourse-cdn.com/v4/letter/g/278dde/32.png) [@getabc](https://forum.inductiveautomation.com/u/getabc)\
**Post date:** [November 6, 2013, 11:08pm UTC](https://forum.inductiveautomation.com/t/convert-modbus-temperature-value/7523/3 "2013-11-06T23:08:00Z")

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Thank you JordanCClark!!

Works perfectly 🙂 ![:thumb_right:](https://us1.discourse-cdn.com/inductiveautomation/original/1X/2026e28c0c425034352c1b75807edf956adc75f4.gif ":thumb\_right:")