I don't know if this will help .... but Daniels GC use the 0-4095 raw counts as well. To get them into DCS and make them read correctly I do the following. Take the full scale range from Tricon and divide by 4095 (200 psig / 4095 = 0.04884) Set SCI = 0 Kscale = 0.04884 The value should match Tricon value. I have never tried this will a Tricon, but sounds like the same thing we have going on with the Daniels GC. something about reals, integers and floating points. Had it all straight in my feeble mind at one time and can't remember now. Troy L. Brazell Duke Energy Field Services Sr. Process Control Analyst ISA CCST Phone (405) 263 4810 ext. 24 Cell (806) 898 4340 Okarche C&M Route 4 P.O. Box 40 Okarche, OK. 73762 "Gregory A Hurwitt" To: foxboro@xxxxxxxxxxxxx <hurwitg@basf-cor cc: p.com> Subject: [foxboro] Analog values from Triconex to I/A via Modbus Int 30 Sent by: foxboro-bounce@fr eelists.org 02/09/2005 11:32 AM Please respond to foxboro Hello list, I am trying to communicate a few analog values from a Triconex system (Tricon V9.x) to I/A (V6.x) via a Modbus Integrator 30. These values are calculated in the Triconex, and stored in read-aliased real memory locations. (Alias numbers beginning at 33001.) My MDSCAN block is set up with DATYPE = 4 (read-only analog data beginning at address 30000). I am aware that only the integer portion of my value will be communicated, and this is perfectly acceptable for my application. The problem I am having is that a value of 0.0 at the Triconex is interpreted as 819 raw counts in my Mod Int 30 AIN block. This happens regardless of the setting for SCI in the AIN block. (Makes sense; signal conditioning is applied *to* raw counts to generate the measurement value.) A value of 32767.0 at Triconex is seen as 32767 counts at the AIN block. The "offset" in the raw counts is linear between these two endpoints, so I have been able to come up with KSCALE/BSCALE factors that allow me to work around the problem. IMO, this is a very ugly workaround. Of course, anyone who has worked with Triconex at all knows that 0-20 mA analog inputs are interpreted in the system as 0-4095 counts, and that 819 counts is the exact value for 4 mA. It seems like I/A is trying to "help" me by accounting for a 4mA zero signal, although it does seem backwards (819 in Triconex should be interpreted as 0 in I/A, not vice versa as is happening). However, none of this applies to my situation, since I'm not looking at an analog input in counts in Triconex, but rather a calculated value already in engineering units. I simply want to communicate the existing value with no modification. Is there an SCI setting that "reverses" the 819 count offset? I sure don't see one in the documentation. Or do I have something configured incorrectly? Or is this a known limitation of the Modbus Integrator 30? Thanks, Greg Hurwitt BASF Freeport _______________________________________________________________________ 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