From cast10-request@bevo.che.wisc.edu Wed Nov 4 08:35:32 1998 Received: (from slist@localhost) by bevo.che.wisc.edu (8.8.8/8.8.8) id IAA21745 for cast10-dist@bevo.che.wisc.edu; Wed, 4 Nov 1998 08:35:32 -0600 (CST) Resent-Date: Wed, 4 Nov 1998 08:35:32 -0600 (CST) Message-Id: <199811041435.IAA00291@bevo.che.wisc.edu> X-To: X-Sender: samc@cicsserver X-Mailer: QUALCOMM Windows Eudora Light Version 3.0.5 (32) Date: Tue, 03 Nov 1998 12:15:09 +1100 To: cast10@bevo.che.wisc.edu From: Sam Crisafulli Subject: CAST: FREE Excel PID Calculator Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-CAST-Category: software Resent-Message-ID: <"ogKGWyukL0H.A.DX.0YGQ2"@bevo.che.wisc.edu> Resent-From: cast10@bevo.che.wisc.edu X-Mailing-List: X-Loop: cast10@bevo.che.wisc.edu Precedence: list Resent-Sender: cast10-request@bevo.che.wisc.edu Sender: cast10-request@bevo.che.wisc.edu ----------------------------------------------------------------- NOTE: Past postings on the CAST10 Email List are archived on the World Wide Web at http://www.che.wisc.edu/cast10 ----------------------------------------------------------------- Note added by list moderator. Advertising by companies is not normally allowed; this program was previewed by a process control Professor and recommended for distrubtion on the CAST email list. FREE Excel PID Calculator ************************* http://www.cicsauto.com.au (In download section) CICS Automation Pty Ltd has developed an Excel spreadsheet for calculating P, I and D parameters for a range of DCS and PLC systems. It utilises the IMC (Internal Model Control) model-based control design methodology to calculate the values depending on the process characteristics (lag, lag+dead-time, integrating, etc) as well as process parameters (gain, time-constant, dead-time, etc). A step by step methodology is explained in the on-line help. Briefly, the procedure is as follows: 1) stabilise the process in manual 2) while in manual, introduce a step change into the Manipulated Variable(MV) and observe the response 3) return to auto and repeat step 1 and 2 again if required 4) characterise response as i) lag, ii) lag + dead-time, iii) integrator iv) integrator plus deadtime, v) second order, etc 5) measure relevant parameters such as gain, time constant, etc 6) choose Excel page that closest corresponds to the response curve 7) enter process parameters into spreadsheet 8) choose the "beta" parameter which determines the closed-loop response time (how agreesive the controller is) 9) read P, I and D values from spreadsheet and then enter into DCS or PLC This methodology and spreadsheet has been adopted company-wide by several process industry companies. Used by technicians, electricians, process engineers, metallurgists, control engineers. If the DCS and PLC you use is not listed in the spreadsheet, it is easy to do your own translations. 1) Go to the DCS or PLC detailed documentation and find out which type of PID structure it is: a) series b) parallel or c) ideal 2) Use the P, I and D values of the Generic Forms as a starting point 3) If the Integral term is time/repeat (eg. minutes/repeat) then take the inverse of the I value (eg. 1/Igeneric = Inew) If the Integral term is repeats/time, then leave as is 4) If the time units are minutes, then multiply or divide by 60 to translate to minutes If the time units are seconds, then leave as is. Alternately, Fax us the PID data sheets (+61 2 4965 6705) and we will do the translation when time permits. Please feel free to download the spreadsheet and use it as you wish. Comments are very much appreciated, as well as reporting successes and failures. Please forward any new translation you do so that we can add them to the PID Calculator. Also, please revisit from time to time as we add more and more DCS and PLC systems. Sam Crisafulli CICS Automation Pty Ltd samc@cicsauto.com.au *************************************************************** Sam Crisafulli Ph. +61 2 4965 6700 (office) CICS Automation Pty Ltd Ph. +61 2 4965 6702 (direct) PO Box 570 FAX +61 2 4965 6705 Wallsend NSW 2287 Australia Mobile: +61 419 402 003 WWW: http://www.cicsauto.com.au Email: samc@cicsauto.com.au ***************************************************************