Why not use SPRATE, RAMP & Target? Rgds, Dirk -----Original Message----- From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On Behalf Of Adam.Pemberton@xxxxxxxxxxxx Sent: maandag 16 oktober 2006 23:51 To: foxboro@xxxxxxxxxxxxx Subject: Re: [foxboro] Check against entering ridiculous values Thanks Rocco I wasn't aware of the SPHLIM and SPLLIM parameters and so thank you. A bit embarrassing really. I thoroughly checked out the PID but not the PIDA.=20 However in this case these limits won't be enough on there own since the issue with the autoclaves is that the required setpoint range is quite high, but the short term change must be limited. I like your two possible options, that of 1) limiting the setpoint based on prevailing conditions and 2) using a special overlay.=20 I can see how to limit the setpoint but don't know how to implement this special overlay. Could you please elaborate? I guess I can't see where the checking code would go. =20 Regards Adam =20 -----Original Message----- From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On Behalf Of Penndorf, Rocco (RP) Sent: Monday, 16 October 2006 4:05 PM To: 'foxboro@xxxxxxxxxxxxx' Subject: Re: [foxboro] Check against entering ridiculous values =20 =20 Adam, =20 there are certainly some options how to accomplish this. The most simple one might be to clamp the range (using SPHLIM, SPLLIM parameters of PIDA) where you can enter a setpoint. But this approach does not provide much flexebility in terms of operation of this controller. On some occurances you might want to be able to enter a very low setpoint, what is then not possible.=20 The second option takes care of this. You also can make this clamp depending on operating conditions, but this would require an additional CALC block, what changes the SPHLIM and SPLLIM parameters. In our plant we are using a special PIDA overlay, what checks if the new entered setpoint deviates more than 10% from the old setpoint and notifies the operator. =20 =20 Best Regards Rocco=20 =20 -----Original Message----- From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On Behalf Of Adam.Pemberton@xxxxxxxxxxxx Sent: Monday, October 16, 2006 2:04 AM To: foxboro@xxxxxxxxxxxxx Subject: [foxboro] Check against entering ridiculous values =20 =20 We had an incident on Saturday where an operator accidently entered a very low setpoint (5kPa when it should be >2200 kPa) on the pressure control for one of our Autoclaves. This caused the vent valve to open to 100% and the clave to rapidly depressurize. This is a potentially catastrophic incident since high venting in an Oxygen rich environment can cause a major fire. =20 =20 We are at the final stages of a migration from Display Manager to FoxView. In order to help these guys with the transition, we have provided them with one Exceed XTerm running Display Manager off our engineering development AW. =20 =20 =20 This incident illustrated a number of issues : =20 - The operator claimed that the FoxView workstation he was working on (Blade 150) locked up and he had to move to Display Manager on the Xterm to correct the erroneous value. =20 - We have disabled the arrow keys on FoxView while we wait for 9.0.2. Using the arrows on some parameters gives very large changes. =20 - We need a good way to prevent ridiculous values being entered in situations such as this. =20 =20 =20 My question from all this is what have people in this group done to resolve the issue of preventing operators from entering dangerous values? One suggestion was to have a popup appear if the change is greater than 200kPa (for example). Is there an easy way of doing this? =20 All our workstations are Sun Blade 150's or PC's running Exceed (usually V7). I/A is version 7.1.1. FoxView is version 9.0.1 =20 =20 =20 Adam Pemberton Site Electrical & Control Systems Engineer Lihir Gold Limited =20 Ph: +675 9865 655 Fax: +675 9865 666 Mob: Nogat Postal: Australia: GPO Box 905, Brisbane, QLD 4001 PNG: PO Box 789, Port Moresby, NCD =20 =20 =20 =20 =20 =20 _______________________________________________________________________ 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 =20 foxboro mailing list: http://www.freelists.org/list/foxboro to subscribe: = mailto:foxboro-request@xxxxxxxxxxxxx?subject=3Djoin to unsubscribe: = mailto:foxboro-request@xxxxxxxxxxxxx?subject=3Dleave =20 =20 =20 _______________________________________________________________________ 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 =20 foxboro mailing list: http://www.freelists.org/list/foxboro to subscribe: = mailto:foxboro-request@xxxxxxxxxxxxx?subject=3Djoin to unsubscribe: = mailto:foxboro-request@xxxxxxxxxxxxx?subject=3Dleave =20 =20 Re: [foxboro] Check against entering ridiculous values =20 =20 _______________________________________________________________________ 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 =20 foxboro mailing list: http://www.freelists.org/list/foxboro to subscribe: = mailto:foxboro-request@xxxxxxxxxxxxx?subject=3Djoin to unsubscribe: = mailto:foxboro-request@xxxxxxxxxxxxx?subject=3Dleave =20 _______________________________________________________________________ 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: http://www.freelists.org/list/foxboro to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave