Alex, I understand everything you said except I don't understand if the script is custom for each PIDA or generic for all PIDA's. Also, are you doing the math internal to the script or passing off to a math or calc block? For Tim's purpose, the script would need to know either the allowable engineering unit limit per each controller or the high and low scale and a percentage. For our PIDA's, we use a generic overlay. We define upper and lower setpoint limits SPHLIM, SPLLIM and every block has SPROPT set to 3 = (Target Over Time), and the generic overlay has an entry window for .SPTARG and .SPRATE which always indicates Minutes to ramp to target. Once entered on the generic overlay the operator can toggle .SPRAMP to begin a ramp to the new target. This gives them time to insure that their entry is valid before beginning a ramp. Ramping the setpoint is also much nicer to the process than bumping a setpoint by 5% of scale all at once. We have a color convention that allows the user to look at the base graphic and know if a setpoint is currently being ramped. Our entire strategy is generic and consistent. Tom VandeWater Control System Developer/Analyst Dow Corning Corporation Carrollton, KY USA -----Original Message----- From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On Behalf Of Johnson, Alex (Foxboro) Sent: Thursday, March 31, 2005 1:48 PM To: foxboro@xxxxxxxxxxxxx Subject: Re: [foxboro] global variable setpoint limiting I've usually done this by: 1) Creating a pick point on the main graphic that loads P1 with the tag (C:B.SPT) and raises an overlay (generic). 2) On the overlay a) Displaying the current value Connects to $P1 b) Having a data entry box Connects to P2 c) Having a Confirm button Runs a script that validates the setpoint and either: i) Makes the change or ii) Clears P2 and re-raises the overlay d) Having a Cancel button Closes the overlay Works pretty well and can easily be implemented on your "standard" library element used for showing the setpoint. Hope this helps. Regards, Alex Johnson Invensys Process Systems Invensys Systems, Inc. 10707 Haddington Houston, TX 77043 713.722.2859 (voice) 713.722.2700 (switchboard) 713.932.0222 (fax) ajohnson@xxxxxxxxxxx -----Original Message----- From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On Behalf Of William C. Ricker Sent: Thursday, March 31, 2005 12:25 PM To: foxboro@xxxxxxxxxxxxx Subject: Re: [foxboro] global variable setpoint limiting Note that a MATH block takes a quarter the space of a CALC. ==== On one site where ops entry error was a concern, we took away all numeric operator entry fields and gave them only ramp keys. Crude, but effective. ==== Regards, William C. Ricker FeedForward, Inc. Marietta, GA USA 770.426.4422 wcricker @ feedforward.com _______________________________________________________________________ This mailing list is neither sponsored nor endorsed by Invensys Process Systems (formerly The Foxboro Company). Use the info you obtain here at your own risks. Read http://www.thecassandraproject.org/disclaimer.html foxboro mailing list: //www.freelists.org/list/foxboro to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave _______________________________________________________________________ This mailing list is neither sponsored nor endorsed by Invensys Process Systems (formerly The Foxboro Company). Use the info you obtain here at your own risks. Read http://www.thecassandraproject.org/disclaimer.html foxboro mailing list: //www.freelists.org/list/foxboro to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave _______________________________________________________________________ This mailing list is neither sponsored nor endorsed by Invensys Process Systems (formerly The Foxboro Company). Use the info you obtain here at your own risks. Read http://www.thecassandraproject.org/disclaimer.html foxboro mailing list: //www.freelists.org/list/foxboro to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave