Re: [foxboro] Word-Swaping on Modbus Interface Micro I/A (32-bit IEEE-Floating Point)

Steve,

thanks, but my Real value is 32-bit IEEE-754 Floating Point format, lik=
e
this:



Decimal Value Entered: 12.34


Single precision (32 bits):


Binary:=A0=A0=A0=A0=A0Status: normal
|-------------+--------------------------------------------------------=
--+------------------------------------------------|
|             |                                                        =
  |                                                |
|    Bit 31   |                                                        =
  |                                                |
|   Sign Bit  |                       Bits 30 - 23                     =
  |                   Bits 22 - 0                  |
|      0      |                      Exponent Field                    =
  |                   Significand                  |
|     0: +    |                         10000010                       =
  |           1 .10001010111000010100100           |
|     1: -    |       Decimal value of exponent field and exponent     =
  |        Decimal value of the significand        |
|             |                       130 - 127 =3D 3                  =
    |                    1.5425000                   |
|             |                                                        =
  |                                                |
|             |                                                        =
  |                                                |
|-------------+--------------------------------------------------------=
--+------------------------------------------------|




Hexadecimal: 414570A4=A0=A0Decimal: 12.340000



The FRIN Block read it in the right way, if the Modbus-Words are in the=

right order. But it isn't in my case.

Regards

Rolf Reber
____________________________________
EMS-CHEMIE AG
Business Unit EMS-SERVICES
Abt. Anlagenbau / Prozessleitsysteme
Reichenauerstrasse
CH-7013 Domat/Ems

Phone: +41 (0) 81 / 632 71 49
Fax:      +41 (0) 81 / 632 74 04
mailto: rolf.reber@xxxxxxxxxxxxxx
http://www.emsservices.ch


|---------+---------------------------->
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|         |           mobil.com        |
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Rolf,

We have done this with RIN blocks on a Modbus interface.  The "trick" i=
s to
use 2 separate RIN blocks for each 16-bit word.  Then use a CALC block =
to
manipulate the two values from the RIN blocks to determine the original=

value.

For example, there is a value transmitted over the Modbus interface tha=
t is
67098.2 originally.  The words are transmitted such that the first word=
 is
the low order bits and the second word is the high order bits.  The fir=
st
word is pulled into a RIN block that has an MGAIN value of 0 (zero).  T=
he
second word is pulled into a RIN block that has a MGAIN value of 1000
(based upon the documentation of the Modbus sending device and how the
interface is designed).  The RIN blocks are therefore "reading" 98.2 fo=
r
the low order and 67000 for the high order.  Pull these RIN blocks into=
 a
CALC block and simply add them together.

Hope this helps.


Steve Shimp
Maintenance & Systems Engineer
ExxonMobil Paulsboro Lube Plant
phone: 856.224.5059      cell: 609.820.8501      fax: 856.224.5030
email:  steve.shimp@xxxxxxxxxxxxxx

foxboro-bounce@xxxxxxxxxxxxx wrote on 02/14/2006 08:00:55 AM:

>
> Hi List,
>
> our I/A-System is Unix V6.4 and Micro I/A V6.2.5 with 2 Modbus serial=

> Interfaces attached. I would like to read/write data from/to a Modbus=

> Device (Brabender weighing unit) with FRIN /FROUT blocks. But the two=

16bit
> Modbus Words for a real value are in wrong order.  Example: Value 12.=
34
in
> the Modbus Adresses 47200 and 47201 (Value Hex 70A4 4145) will be
displayed
> on FoxView as 4017238209...................... How can I change the O=
rder
> of the Modbus Adresses to 47201 and 407200 (Value Hex 4145 70A4) on t=
he
> I/A-System? There is no way to change it on the Modbus Device!
>
> Thanks for helping,
>
> Regards
>
> Rolf Reber
> ____________________________________
> EMS-CHEMIE AG
> Business Unit EMS-SERVICES
> Abt. Anlagenbau / Prozessleitsysteme
> Reichenauerstrasse
> CH-7013 Domat/Ems
>
> Phone: +41 (0) 81 / 632 71 49
> Fax:      +41 (0) 81 / 632 74 04
> mailto: rolf.reber@xxxxxxxxxxxxxx
> http://www.emsservices.ch



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