Modbus register readings, double type Shared Variable 32000

Question

Hello
I am new to labview and modbus and have been trying to communicate with a control card using the VIs in the standard modbus library in labview 8. This might be a very simple question, it relates to the output of the "read holding register" or "function code 0x03" . All the results I have been getting are in 5 digit decimal form, I have read in another post that this may be the "double type Shared Variable" and that it can be converted or typecasted to "ieee 754 type" i.e. as actual measurement values. I was wondering if it is possible for 5 digit "double type shared variable" that are greater than the 32000, i.e such as 50119 or 50294, to be converted to "ieee 754 type". Or even if there are standard methods that can perform this type of conversion in general.
Thanks in advance

Answer 1

Maybe this will help.
http://forums.mrplc.com/index.php?showtopic=30
http://www.simplymodbus.ca/FAQ.htm#Types
What are data types?
The example for FC03 shows that register 40108 contains AE41
which converts to the 16 bits 1010 1110 0100 0001
Great! But what does it mean? Well, it could mean a few things.
Register 40108 could be defined as any of these 16-bit data types:
     A 16-bit unsigned integer (a whole number between 0 and 65535)
                    register 40108 contains AE41 = 44,609 (hex to decimal conversion)
     A 16-bit signed integer (a whole number between -32768 and 32767)
                                                        AE41 = -20,927
              (hex to decimal conversion that wraps, if its over 32767 then subtract 65536)
     A two character ASCII string (2 typed letters)
                                                        AE41 = ® A
     A discrete on/off value (this works the same as 16-bit integers with a value of 0 or 1.
                                              The hex data would be 0000 or 0001)
Register 40108 could also be combined with 40109 to form any of these 32-bit data types:
     A 32-bit unsigned integer (a number between 0 and 4,294,967,295)
                             40108,40109 = AE41 5652 =  2,923,517,522
     A 32-bit signed integer (a number between -2,147,483,648 and 2,147,483,647)
                                                       AE41 5652 = -1,371,449,774
      A 32-bit double precision IEEE floating point number.
      This is a mathematical formula that allows any real number (a number with decimal
       points) to represented by 32 bits with an accuracy of about seven digits.
                                                       AE41 5652 = -4.395978 E-11
      Here is a spreadsheet IEEE float calculator for inputs of 4 bytes or 2 words.
      To download a copy, right click and select Save Target As...
     A four character ASCII string (4 typed letters)
                                                         AE41 5652 = ® A V R
More registers can be combined to form longer ASCII strings.  Each register being used to store two ASCII characters (two bytes).