I've just now read this message, so my comments are probably too late, but... A CHARC block will not produce a BCALCO value unless PRIBLK is set. And if PRIBLK is set, you need a control block upstream to terminate the chain. For applications where you have a CALC block or something else upstream that needs the back-calculated CHARC output, eg in a split-range function, you can drop a BIAS block in between, with a PRIBLK=0, to keep the CHARC block happy. eg. [CALC] [BIAS] [CHARC] [AOUT] OUT --> RBIAS --> MEAS --> MEAS RI01 <-- BCALCO <-- BCALCO <-- BCALCO PRIBLK=0 PRIBLK=1 PRIBLK=1 Note also that different intialisation contstraints apply to a CHARC when PRIBLK is set. You can't have a reversal in the characterisation, eg output rising with input and then falling, because a back-calcuation would not be possible. But with PRIBLK cleared, this is allowed. cheers, Con O'Brien -----Original Message----- From: Joerg Wierz [mailto:jwierz@xxxxxxxxxx] Sent: Thursday, 20 March 2003 2:08 AM To: foxboro@xxxxxxxxxxxxx Subject: Re: [foxboro] 3 CHARC blocks cascaded Hi, you didn't get any answers because you didn't describe your problem completely (include top and bottom of your information stream !). What do you want to do? If you want to maipulate a measurement you don't need any backcalculation (forget about BCALCI/O, PRIBLK=0). If you want to adapt a nonlinear valve characteristic in a control loop or somehing like that, then you should implement back calculation, but you'll also have to take your AOUT and PID block into the boat. PID CHARC AOUT OUT -------> MEAS OUT -------> MEAS BCALCI<----- BCALCO BCALCI<-----BCALCO PRIBLK=0 PRIBLK=1 PRIBLK=1 Add as many CHARC's inbetween as you like. J.Wierz ----- Original Message ----- From: "Tamer Ahmed" <tmahmoud1973@xxxxxxxxx> To: <foxboro@xxxxxxxxxxxxx> Sent: Sunday, February 09, 2003 10:07 AM Subject: [foxboro] 3 CHARC blocks cascaded > > we have about 56 points and we want to build 3 CHARC > blocks in cascade > we are using I/A 6.2.1 and we are trying to build > these CHARC blocks by connecting the 3 CHARC blocks as > follows: > > CHARC1 CHARC2 CHARC3 > > OUT -----> MEAS OUT -----> MEAS > BCALCI<----- BCALCO BCALCI<-----BCALCO > > PRIBLK=0 PRIBLK=1 PRIBLK=1 > > but with these connections we the cascade loop are > open. any one can help > > > __________________________________________________ > Do you Yahoo!? > Yahoo! Mail Plus - Powerful. Affordable. Sign up now. > http://mailplus.yahoo.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