News:
Home
Help
Search
Login
Register
April 30, 2026, 02:48:25 PM
1 Hour
1 Day
1 Week
1 Month
Forever
Login with username, password and session length
Host Engineering Forum
»
General Category
»
General Discussion
»
Conversion of values read via ModbusTCP
« previous
next »
Print
Pages: [
1
]
Author
Topic: Conversion of values read via ModbusTCP (Read 12195 times)
tdecant_GMI
Newbie
Posts: 2
Conversion of values read via ModbusTCP
«
on:
March 30, 2009, 10:56:59 AM »
I am reading in VMemory values with VB. In the PLC the values I want to view reside as Real. What is the conversion? I am able to convert the Byte array to a readable Decimal value but I don't know how to translate the 4 Bytes (the 2 VMemory locations) to a Real.
Thanks.
Logged
Greg
HostTech
Host Moderator
Hero Member
Posts: 702
Hmmm...
Re: Conversion of values read via ModbusTCP
«
Reply #1 on:
March 31, 2009, 12:30:12 PM »
If I'm understanding you properly, then the format of the real number in V-memory is IEEE 32-bit format. If, for example, you are using a DL205, then in the d2user manual on page 5-90 is a graphical description of this format.
Logged
There are two types of people in the world; those that can extrapolate from incomplete data sets.
franji1
Bit Weenie
Host Moderator
Hero Member
Posts: 3806
Re: Conversion of values read via ModbusTCP
«
Reply #2 on:
March 31, 2009, 12:49:30 PM »
If you have 2 V memory locations from the PLC, then the 32 bit IEEE floating point number SHOULD work as follows:
V2000 and V2001 in 2 16 bit locations in VB as type WORD (I'm not a VB buy, but you should know how you are storing your 16 bit word in VB). Likewise the result would be in a 32 bit float - not sure what that is in VB (VB6? VB.Net?)
WORD MyV2000
WORD MyV2001
float MyVB32BitFloat
HIWORD of MyVB32BitFloat is set to MyV2001
LOWORD of MyVB32BitFloat is set to MyV2000
Logged
There are only 10 kinds of people in this world: those who know binary, and those who don't
tdecant_GMI
Newbie
Posts: 2
Re: Conversion of values read via ModbusTCP
«
Reply #3 on:
March 31, 2009, 04:39:08 PM »
Thanks.
Logged
Print
Pages: [
1
]
« previous
next »
Host Engineering Forum
»
General Category
»
General Discussion
»
Conversion of values read via ModbusTCP