Re: [foxboro] CALC block
- From: "Ray J Chouinard" <rjc2@xxxxxxxxxxxxxxxx>
- To: foxboro@xxxxxxxxxxxxx
- Date: Wed, 7 Jan 2004 11:22:16 -0500
Bret,
There can't be a difference between the two readings. Although the source
of RI01 may have changed while the block is being processed, the block
only reads this value once before processing all the steps.
Ray Chouinard
MeadWestvaco
Escanaba, MI
"Bolting, Brett C." <Brett.Bolting@xxxxxxxxxxxxxxxx>
Sent by: foxboro-bounce@xxxxxxxxxxxxx
01/07/2004 09:18 AM
Please respond to foxboro
To: <foxboro@xxxxxxxxxxxxx>
cc:
Subject: Re: [foxboro] CALC block
Well, for my two cents...
Yes, I suppose if your upstream block and/or our process is fast enough =
there could be different values between those two reads..
You could either adjust your period and phasing on the two blocks or =
better yet I think would be to just read the value you now have=20
going to RI01 to a memory location the pull that value into your =
sequence form the memory location with a LAC Mxx command.
Brett Bolting
Process Control Specialist
Equistar Chemicals
(361) 572-2570
(361) 270-8197 beeper
--
"They that would give up essential liberty for temporary safety deserve =
neither liberty nor safety."
-- Benjamin =
Franklin
> -----Original Message-----
> From: IQUEIROLOO@xxxxxxxxxxxxx [SMTP:IQUEIROLOO@xxxxxxxxxxxxx]
> Sent: Wednesday, January 07, 2004 7:47 AM
> To: foxboro@xxxxxxxxxxxxx
> Subject: [foxboro] CALC block
>=20
> Hi list, I have a question about the CALC block. Suppose that we have =
a =3D
> CALC block with this instruction in the first line:
>=20
> Step 1 IN RI01
>=20
> and the same instruction is repeated in the 40th line, as follows:
>=20
> Step 40 IN RI01
>=20
> If the value of RI01 has changed in the time between those two steps =
in =3D
> the same BPC, the values that the block will read will be different?.
>=20
> Suppose that the CALC block and the block where the value of the RI01 =
=3D
> comes from are in the same compound.
>=20
> Thanks,
>=20
> Ignacio Queirolo Olivera
> Repsol YPF
> Tel: +54 221 429-8400 ext. 26481
> Fax: +54 221 429-8400 ext. 26272
> mailto:iqueiroloo@xxxxxxxxxxxxx
>=20
>=20
>=20
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