CCS/EK-TM4C1294XL: Transfer float value over Modbus RTU using the IEEE 754

Hi Hani,

If you need transmit IEEE 754 float number via Modbus you should not convert float to integer. You should simple send float number via two Modbus registers. Only important this is a which endian is supported by your Modbus master.

BTW ... it does not exist anything like a int32 IEEE 754.

Jan

Hi Jan

my concern is how to translate the float to IEEE754, then sending the IEEE754 over modbus.

BR

Hi,

Float = IEEE754.

Jan

Hi, this is what i want to get, is there any CCS tool / library supporting this?

Hi,

Yes, all float point variables and calculations are nativity done at IEEE754. Also TM4C1294 have FPU (Floating-Point Unit) for single-precision flaot calculations (=IEEE754).

Jan

OK, but how to extract the exponent & mantissa from the float?

Hi,

Why you need extract exponent and mantissa from float? If you want send separately exponent and mantissa in two Modbus registers, then I am almost 100% sure that Modbus master will not be able deal with this. When you send IEEE754 float via Modbus then exponent and mantissa are not send separately. Please read this.

Function for working with IEEE754 floats you find at <math.h> -e.g. https://www.tutorialspoint.com/c_standard_library/c_function_frexp.htm

Jan

Thank you Jan for your support , I think this may help.