Re: [foxboro] RE : Hard-coding the block inhibit parameters

Terry,

I appreciate the details.  The real purpose of the inquiry was that
during our experimentation it was discovered that hard-coding the 2
inhibit parameters (INHIB & INHALM) only secured the parameter if the
value(s) were high (1); it did not prevent the operator from over-riding
the value(s) set to 0.  I was just shocked and trying to get an
explanation as I always thought hard-coding "any" parameter value
"always" secured the parameter no matter what the value.  Unless I
missed it, no one has explained the reason and if maybe other parameters
have similar traits.  However...

The real issue is that we have planned to secure specific blocks to
prevent the operators from inhibiting (1) critical alarms by hard-coding
0s in the INHIB and/or INHALM (Hex) parameters (C:B.INHIB.0,
C:B.INHALM.0x0003, etc.).  Unless I am missing something, we need to
change to Plan B and will have to connect these parameters to dummy
blocks; one for each combination of inhibits.  Plan A was much
simpler...

Thanks again.


Joseph M. Riccardi
DCS Services - Industrial Process Control

Joe@xxxxxxxxxxxxx
"To give real service you must add something that cannot be bought or
measured with money; and that is sincerity and integrity." - Donald A.
Adams


-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of Doucet, Terrence
Sent: Tuesday, June 26, 2007 11:11 AM
To: foxboro@xxxxxxxxxxxxx
Subject: [foxboro] RE : Hard-coding the block inhibit parameters

I hope that I am not being redundant with any of this information.  The
first item to configure when you want the alarm is the Option parameter.
Each type of alarm has its own parameter name.  As an example, we use
the AIN High/Low Option (HLOP) then you have 
 
0 = No alarming
1 = High and Low absolure
2 = High Abs only
3 = Low abs only
 
So if you only want low alarming then configure a 3 in this parameter
and you never need to worry about high alarms.
 
Once you have your alarm configured then you should connect the .INHSTA
parameter to the INPUTS parameter of a MCIN (no IO) block. Then you can
use the AIN default display - ALARMS - overlay to toggle the inhibits
that you desire. Now go to the default display for the MCIN and you can
view the hex pattern  in the INPUTS:  box. For example if you inhibit
the High and Low Absolute alarms your will see 00030000 displayed.
 
To set only the high and the low inhibit your would set the hex pattern
0x0003 into the AIN.INHALM. Use a program or a script with omsetimp to
write this hex value.
 
Toggling the  AIN.INHIB to a TRUE will inhibit all the configured alarms
in your block.  Setting AIN.INHIB to a FALSE will release the AIN block
to inhibit only those specified by the hex pattern of the INHALM.
Obviously, with INHIB = FLASE and INHALM = 0 all configured alarm
annunciation is enabled.
 
Terry
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