Rich, We had something similar in our plant. Our solution was to change the OSV (Output Span Variance) for the AIN block from its default of 2.0 to 10.0. This gives the AIN additional output range. Your situation may be more severe than what we were dealing with but working with this parameter might help. Thanks, Bob -----Original Message----- From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On Behalf Of Targosky, Richard S. Sent: Tuesday, February 16, 2010 1:54 PM To: 'foxboro@xxxxxxxxxxxxx' Subject: Re: [foxboro] TRKENL and HOLD on PIDA block Thanks to all for their input. TRACK wins over HOLD when TRKENL is set to true so you can put the controller output where you like this way. That was my question. I just finished a TEST of this and TRACK does win over HOLD! The particulars of my case are that 20% OUT will pinch the valve back - and allow the PID block to control once the FI gets back into range. And - yes - we do need to get/keep the valve open to allow the pluggage to clear. I will be driving the valve back to 20% when the Flow Xmitter goes High Off-scale. The cycle you refer to is something we need to look out for. Thanks again - Rick T -----Original Message----- From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On Behalf Of Rick Rys Sent: Tuesday, February 16, 2010 1:41 PM To: foxboro@xxxxxxxxxxxxx Subject: Re: [foxboro] TRKENL and HOLD on PIDA block Richard, A couple of points on your application. Setting CEOPT likely makes no difference, because if your AIN block has BADOPT = 3 (default), the PIDA block goes to hold due to the BAD status, adding ERROR is essentially redundant. Also, TRACK wins over HOLD when TRKENL is set to true so you can put the controller output where you like this way. When you get a line plug, you may not get a LOR (BAD) so the controller will wind up to 100% open valve without going to HOLD. Maybe you need to alarm on high controller output, but why do control actions here?, as keeping the valve wide open is more or less what you want and the flow controller will handle it when the plug breaks free. Not sure if putting the valve at 20% does anything to remove the plug, although maybe it would reduce the bump when the plug finally breaks up. If you set TRKENL (with TRACK = 20%) when the controller output stays high for a sustained time you will get a cyclic behavior and it may not really help much. Maybe what you want to do is to set TRKENL true if the controller output is greater than 19% open and the FLOW is less than 1 or 2% of scale for a sustained 20 seconds, as this would hold the output at 20% via TRKENL and release when the plug breaks up. Rick Rys P.E. www.R2controls.com 1 Cherry Street Mansfield, MA 02048 508-339-6633 Home Office 508-369-5186 Mobile _______________________________________________________________________ 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 The information contained in this message and any attached files may be privileged and/or confidential and protected from disclosure. If you are not the intended recipient, any disclosure, copying, distribution or use of any of the information contained in or attached to this transmission is strictly prohibited. If you have received this transmission in error, please so notify the sender immediately without reading it. Also, please promptly destroy the original transmission and its attachments. Any views or opinions presented in this message or attachments are those of the author and do not necessarily represent those of KapStone Paper and Packaging Corporation or its subsidiaries. _______________________________________________________________________ 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