Re: [foxboro] CALC BLOCK QUESTION
- From: "Brazell, Troy L Jr" <TLBrazell@xxxxxxxxxxxxxxxx>
- To: <foxboro@xxxxxxxxxxxxx>
- Date: Thu, 8 Feb 2007 13:13:50 -0500
Okay Duc,
The calculation that I now have works great at 85 degf, so what I need
to know now is how to calculate LN in a CALC block.
As the result of temp x .0321 increases the factor 2.718281828459 should
change as well, correct?
Please be gentle, I am not an engineer!
Thanks
Troy
**************************
Troy Brazell
DCP Midstream
ISA CCST
Sr. Process Control Analyst
Office 405-263-4130
Cell 405-301-2994
tlbrazell@xxxxxxxxxxxxxxxx
**************************
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of duc.do@xxxxxxxxxxxxxx
Sent: Thursday, February 08, 2007 10:32 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] CALC BLOCK QUESTION
Troy,
I think what throws you off is the similarly-named functions but which
have different actions. While Excel's EXP fucntion is a unary function:
EXP(x) is e^x. CALC's (and CALCA) EXP function is a diadic function. It
is merely EXP(x,y) =3D3D x^y.
To replicate Excel's EXP function, you need the value of e (which is
defined as ln(e)=3D3D1, e is, therefore, 2.718281828459). Excel does =
this
for you with the specialized EXP function. The equivalent Excel function
to CALC's EXP is POWER(m,n).
I didn't go through your CALC steps, but I suspect that because EXP uses
the top two stack values while you think it needs one, it returns
unexpected value. (Or one that you didn't expect.)
Duc
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of Brazell, Troy L Jr
Sent: Thursday, February 08, 2007 11:06 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] CALC BLOCK QUESTION
Can you explain what RI02 is and where you got it from?
What I am trying to do is:
Excel formal EXP=3D3D3D(Temp*0.0321)*0.0466
IA
RI01 =3D3D3D gas temperature (this can range from 60 degf to 200 degf
M01 =3D3D3D 0.0321
M02 =3D3D3D 0.0466
Steps
1 IN RI03
2 IN M01
3 MUL
4 STM M20
5 LAC M20
6 EXP M20
7 STM M21
There will be additional steps for pressure and flow.
When I use 85 for the inlet temp I get a return of 15.4674
Thanks
Troy
**************************
Troy Brazell
DCP Midstream
ISA CCST
Sr. Process Control Analyst
Office 405-263-4130
Cell 405-301-2994
tlbrazell@xxxxxxxxxxxxxxxx
**************************
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of duc.do@xxxxxxxxxxxxxx
Sent: Thursday, February 08, 2007 9:50 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] CALC BLOCK QUESTION
Troy,
Here's my test CALC block running the EXP function:
NAME CALCTEST
TYPE CALC
RI01 2.7285
HSCI1 100.0
LSCI1 0.0
DELTI1 1.0
EI1 %
RI02 2.718281828459
HSCI2 100.0
LSCI2 0.0
DELTI2 1.0
EI2 %
STEP01 CST
STEP02 IN RI02
STEP03 IN RI01
STEP04 EXP
STEP05 OUT RO01
STEP06 END
The value displayed in the detail display is rounded off to 2 decimal
places (15.31), so I grab it using omget:
04AW01# ./omgetimp -v DUCTEST:CALCTEST.RO01
DUCTEST:CALCTEST.RO01 (f): 15.3099
Duc
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of Brazell, Troy L Jr
Sent: Thursday, February 08, 2007 10:18 AM
To: Foxboro User Group Foxboro User Group
Subject: [foxboro] CALC BLOCK QUESTION
Content-Type: text/plain;
charset=3D3D3D3D"us-ascii"
Content-Transfer-Encoding: quoted-printable
=3D3D3D3D20
Gentlemen,
I have run into an anomaly.
I am trying to Exponent the following value:
2.7285
Doing this in Excel returns 15.3099
Doing this in IA returns 15.4674
This on a water vapor calculation and the difference throws my
calculations way off!
Any help will be greatly appreciated!
Thanks,
Troy
=3D3D3D3D20
=3D3D3D3D20
=3D3D3D3D20
**************************
Troy Brazell
DCP Midstream
ISA CCST
Sr. Process Control Analyst
Office 405-263-4130
Cell 405-301-2994
tlbrazell@xxxxxxxxxxxxxxxx
**************************
=20
=20
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