How about this method using the standard blocks: 3 DTIME AND 3 CALC BLOCKS arranged as follows All DTIME blocks have DTOPT = 0 to insure input averaging over the DT period. All blocks can run at perhaps 0.5 sec period. Number of BUCKETS is 8 to fit # inputs in the CALC or CALCA. DTIME1 DT = 43200/8=5400 (# minutes in 30 days/8 buckets) DTIME2 DT = 43200/8^2=675 DTIME3 DT = 43200/8^3=84.375 CALC1 ADD DTIME1.BKT_1 to BKT_7 +CALC2.RO01 OUT RO01 (30DAY AVE) CALC2 ADD DTIME2.BKT_1 to BKT_7 +CALC3.RO01 OUT RO01 CALC3 ADD DTIME3.BKT_1 to BKT_8 OUT RO01 In this way the 30 day average will update stepwise about every 10.5 minutes and the average will be done using every flow value (each 0.5 seconds) over the 30 day period. I.e. average of some 5,184,000 values. Rick Rys www.R2controls.com 1 Cherry Street Mansfield, MA 02048 508-339-6633 Home Office 508-369-5186 Cellular _______________________________________________________________________ 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