Real numbers via rs-232

[tipper]

I am communicating with a PLC using Modbus. The PLC is outputing its data to me in as a 4 byte real number. To view the data I am converting it to hex and displaying the hex on my screen but I cannot figure out how to grab the 4 bytes from the middle of my string and convert them to a single real number.
Any suggestions would be appreciated.

Thanks
Jerry

[dglienna]

is it a 4-digit number, or a 4-byte LONG number?

[tipper]

I was told it is a 4 byte real number. When I view it as ASCII it does not make any real sense as to how to convert it. The PLC stores the data in BCD as well and I have taken that data to compare it to the real number value and cannot see how they relate. Unfortunately the BCD location will change so I cannot use that for my program.

Wish I had more information to give you, but that is all I have.

Thanks

[Maven]

I was told it is a 4 byte real number. When I view it as ASCII it does not make any real sense as to how to convert it. The PLC stores the data in BCD as well and I have taken that data to compare it to the real number value and cannot see how they relate. Unfortunately the BCD location will change so I cannot use that for my program.

Wish I had more information to give you, but that is all I have.

Thanks

http://www.ray.masmcode.com/tutorial/fpuchap2.htm#real4

[tipper]

Thanks,

I read throught the article and now I understand what I am getting. It also gives me an idea of what I have to do to either convert it manually, or revise the way I am bringing in the data to hopefully get VB to do it for me.

Jerry

[dglienna]

i find it hard to believe that it is giving you a floating point number. Convert it to binary and post it here. We'll look at it for you.

[Maven]

Thanks,

I read throught the article and now I understand what I am getting. It also gives me an idea of what I have to do to either convert it manually, or revise the way I am bringing in the data to hopefully get VB to do it for me.

Jerry

If I'm not mistaken a 4 byte real is a visual basic single.