Re: [foxboro] Restricting the operators access to PID blocks

Ricardo,

That idea of using a customised faceplate is cool.  I think it is a very simple 
way if you really don't want the operators to write to the setpoint without all 
the logics required. I do have an issue using this way when an external 
controller is writing into the PIDE.

To build on Sivaram's case, say we want to restrict it because another external 
controller, e.g. an APC controller will write the setpoint to a Manipulated 
Variable (MV), i.e. typically a PIDE/A.  I know PIDE/A SPT para is con/no-set, 
so this means APC can write to the SPT para.  Is this an accepted practice?  

Additionally, if we use the customised faceplate & if operator wants to take 
back control of the MV during an upset, won't the operator have to go to an APC 
MV list page to enable the SPT change?  This means he has an extra step to 
think about during an upset instead of just going to the controller faceplate & 
take back control (by putting it to Manual or Local).

Best regards,
Andriny Rusman
Staff Engineer,
Advanced Process Control,
Group Technology Solutions,
Level 8, Menara Dayabumi
Phone: 03-2783 6317
Petronet: 8-333-6317
Fax: 03-2783 6499
email: andriny@xxxxxxxxxxxxxxx

-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On 
Behalf Of Kevin Fitzgerrell
Sent: Thursday, July 30, 2009 9:57 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] Restricting the operators access to PID blocks

Hi Sivaram,
Alternatively, you can connect the RSP and the LR parameters to other blocks
and use those as your master - CALC block works nice for locking down a
group of controls.  When your master block sets the LR of the PID to 0, the
operator can change the setpoint as desired.  When LR is set through it's
connection to 1, the RSP comes from the master and can't be changed in the
faceplate.

This can then be documented in your control logic.

This method gets a bit more complicated for inner loops in a cascade
control.

Similar to Ricardo's point, most of the plants I've worked for don't give
the full faceplate and select control to operators - we normally have loop
specific overlays that give only the desired level of control to operations.

Cheers,

Kevin

On Thu, Jul 30, 2009 at 10:45 AM, Ricardo Abech <abech@xxxxxxxxxxxx> wrote:

> Hi Sivaram,
>
> You can do what you want by using a customized faceplate, where the you
> have 2 SPT fields that toggle visibility depending on the condition trigger.
>
> When the condition is true, the SPT field has the PICK configured and then
> SPT changes are allowed. If The condition is False, then is READ ONLY and no
> SPT changes can be performed.
>
> I hope that helps.
>
> Best regards,
>
> Ricardo P. Abech
> Chief Software Architect
>
> LimeWare Company, Inc.
> [USA phone]: (408) 786 5140
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> -----Original Message-----
> From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
> On Behalf Of Sivaram Murugan
> Sent: Wednesday, July 29, 2009 10:14 PM
> To: foxboro@xxxxxxxxxxxxx
> Subject: [foxboro] Restricting the operators access to PID blocks
>
> Hello ,
> We would like to restrict the operators from changing the set points of
> some
> PID blocks , based on some condition.
> Say , if the condition is true , No change in setpoint allowed - but still
> the operators should be able to open and see the face plate.
> If the condition is false , the operators should be able to change the set
> point.
>
> Any idea ,how it can be done ?
> Thank you in advance.
>
>
> -Sivaram
>
>
>
>
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