PLC CPW to 2 ints

Joopie · Nov 22, 2016

I have a micrologix 1400 and am using a CPW block to convert a float to 2 integers. I can read the 2 integers via modbus using a raspberry pi 3, but am having difficulties converting it back to a float value. I am using javascript/python. i have looked into the ieee 754 but cant get it working.

gclshortt · Nov 23, 2016

http://stackoverflow.com/questions/4293230/how-do-i-convert-an-integer-to-a-float-in-javascript

The above link may help you out.
Regards,

exabmorgan · Nov 23, 2016

Probably some kind of memory copy from two words into a floating point variable, it would be language specific.

I did it via a math routines once. Mostly out of boredom. Converting both ways into/out of IEEE754 through base-2 notation. It is in C# but the gist of it is there.

dmroeder · Nov 23, 2016

I think using the struct module in python will do it.

from struct import *
new_value = unpack('f', pack('>hh', integer_1, integer_2))[0]

Epy · Nov 23, 2016

dmroeder said:
I think using the struct module in python will do it.

+1, you beat me to it. struct.unpack what I use in my Python Modbus routines to do this.

PLC CPW to 2 ints

Joopie

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