# Modbus driver reading incorrect floating point values

**URL:** <https://forum.inductiveautomation.com/t/modbus-driver-reading-incorrect-floating-point-values/3768>\
**Category:** Ignition\
**Created:** [December 16, 2011, 5:56pm UTC](https://forum.inductiveautomation.com/t/modbus-driver-reading-incorrect-floating-point-values/3768 "2011-12-16T17:56:31Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Greg.Buehler](https://avatars.discourse-cdn.com/v4/letter/g/ecc23a/32.png) [@Greg.Buehler](https://forum.inductiveautomation.com/u/Greg.Buehler)\
**Post date:** [December 16, 2011, 5:56pm UTC](https://forum.inductiveautomation.com/t/modbus-driver-reading-incorrect-floating-point-values/3768/1 "2011-12-16T17:56:31Z")

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I’m having issues reading a floating point value. It seems I’m getting incorrect values.

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**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\
**Post date:** [December 16, 2011, 6:18pm UTC](https://forum.inductiveautomation.com/t/modbus-driver-reading-incorrect-floating-point-values/3768/2 "2011-12-16T18:18:05Z")

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This one might be hard to diagnose… Is the program you’re viewing them in rounding the floats?

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**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\
**Post date:** [December 16, 2011, 6:19pm UTC](https://forum.inductiveautomation.com/t/modbus-driver-reading-incorrect-floating-point-values/3768/3 "2011-12-16T18:19:01Z")

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Oh, also, is it possible that it was at one point 10.014 and has since changed to 10.000 and your SQLTag deadband is not allowing the change?

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**Author:** ![Greg.Buehler](https://avatars.discourse-cdn.com/v4/letter/g/ecc23a/32.png) [@Greg.Buehler](https://forum.inductiveautomation.com/u/Greg.Buehler)\
**Post date:** [December 16, 2011, 6:36pm UTC](https://forum.inductiveautomation.com/t/modbus-driver-reading-incorrect-floating-point-values/3768/4 "2011-12-16T18:36:24Z")

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It isn’t rounding the floats, and it isn’t a deadband issue as far as I can tell.

I was able to repeat the issue in another set of registers. The PLC was setup to write the value to 410591 - 410592 and everything read fine. We then added the second value to 410593 - 410594 , whereupon Ignition started reading the incorrect value.

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<div class="post-metadata">

**Author:** ![Greg.Buehler](https://avatars.discourse-cdn.com/v4/letter/g/ecc23a/32.png) [@Greg.Buehler](https://forum.inductiveautomation.com/u/Greg.Buehler)\
**Post date:** [December 16, 2011, 6:55pm UTC](https://forum.inductiveautomation.com/t/modbus-driver-reading-incorrect-floating-point-values/3768/5 "2011-12-16T18:55:09Z")

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Nevermind. Addressing was offset by one, and the word order was reversed…

😊

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<div class="post-metadata">

**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\
**Post date:** [December 16, 2011, 6:57pm UTC](https://forum.inductiveautomation.com/t/modbus-driver-reading-incorrect-floating-point-values/3768/6 "2011-12-16T18:57:19Z")

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Woo! mystery solved! Surprised the numbers were coming in anywhere near as accurate in that case though…