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Convert Float to Expnent and Mantissa.

Created by: AlexNolek at: 2/7/2014 2:24 PM (3 Replies)

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2/7/2014 2:24 PM	Rate (0)
AlexNolek Posts: 5 Rating: (0)	Hi, I'm struggling to find two functions, one that converts Float to two values > exponent and mantissa and another that converts it back?? This problem occured when I found out that I couldn't define an input field with representation of Exponent and Mantissa in the HMI Basic software! The issue that I also found really hard is how to easilly use pointers to point at different bitareas in a Real variabled for conversion!?
AlexNolek Posts: 5 Rating: (0)
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2/7/2014 2:52 PM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 1/1/2026 Posts: 6891 Rating: (1368)	AlexNolek Hi, I'm struggling to find two functions, one that converts Float to two values > exponent and mantissa and another that converts it back?? This problem occured when I found out that I couldn't define an input field with representation of Exponent and Mantissa in the HMI Basic software! The issue that I also found really hard is how to easilly use pointers to point at different bitareas in a Real variabled for conversion!? Hello, I hope these discussions would help you: 2 WORTE (high/low) in FLOAT/REAL wandeln displaying exponential in wincc (FP_SEPARATION_SC_NOTATION.jpg ) Best regards, Hamid Hosseini
	Demo Channel on Youtube
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2/7/2014 2:58 PM	Rate (0)
0_Einstein Grandmaster-Expert Joined: 7/7/2010 Last visit: 12/31/2025 Posts: 16342 Rating: (2521)	Maybe another approach that will reduce headache would be either training the end users on how to enter data in the HMI. And, another technical approach would be to set up 2 unique fields on the HMI. Field1 would be a simple decimal value between +/- 10.0 (not including 10), and Field2 would be the power of 10 exponent value. _.________ x 10^__ would be your HMI screen [ Field1 ] [Field2] In the PLC, you convert Field1 and Field2 into your float. IF Field1 < 10.0 and Field1 > -10.0 and Field2 < xx (max for float - 1) Float1 := Field1 * 10^Field2; BadData := FALSE; ELSE BadData := TRUE; Field1 := 0.0 Field2 := 0; END_IF; HMI would display some note when BadData = TRUE Thoughts? Bit manipulating floats seems like it could work. You could also bit mask AND the various bits, but it just seems like a 1970's technique. I am glad more experienced Siemens PLC coders are adding to the discussion.
	Last edited by: huggy_d1 at: 2/7/2014 3:02 PM [someone posted a set of highly technical solutions] science guy
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This contribution was helpful to 1 thankful Users hdhosseini

2/10/2014 10:01 AM	Rate (0)
AlexNolek Posts: 5 Rating: (0)	Hi, made my own ExpMan > Float function: FUNCTION "ExpMan>Float" : Void { S7_Optimized_Access := 'TRUE' } VERSION : 0.1 VAR_INPUT IN_Exp : Int; IN_Man : Real; END_VAR VAR_OUTPUT Out_Float : Real; END_VAR VAR_IN_OUT T_base10 : Real; T_exp : Real; temp3 : Real; END_VAR BEGIN (* Formula: #Out_Float = #IN_Man * 10^(#IN_Exp) ) #T_base10 := LN(10.0); #T_exp := INT_TO_REAL(#IN_Exp); #Out_Float := EXP(#T_base10 #T_exp) * #IN_Man; END_FUNCTION But I haven't been able to do reverse yet.
AlexNolek Posts: 5 Rating: (0)	Last edited by: AlexNolek at: 2/10/2014 10:05 AM
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