Real value deviates, Bug?

PLCnext Engineer
1

When using a Real value I noticed that the value is other then expected. When testing with this is see the folowing:

testreal.pngWhen the value should be 0.02 PLC-NE shows 0.02 but when printed in the HMI the value is 0.019999999995529… When I use the „0.02“ for calculations it also proves the value is not 0.02 but 0.0199…
_testreal 2.png
Are there more people that have noticed this?

2

This is not a bug, it’s related to the precision of 32 bit floating point numbers in IEEE 754 format.
image.pngSource:
IEEE-754 Floating Point Converter This page allows you to convert between the decimal representation of numbers (like „1.02“) and the binary format used by all modern CPUs (IEEE 754 floating point).