Rolling average
Hi all, What I would like is a way to calculate the average position of a valve over the last hour, updated say every minute. and then available as an input for a block. Any ideas? Thanks in advance. Steve Rigby Air Liquide Industrie BV Merseyweg 10 3197 KG Botlek-Rotterdam The Netherlands Tel: +31(0)181-271131 Fax:+31(0)181-271100 Email: [EMAIL PROTECTED] [EMAIL PROTECTED] --- This list is neither sponsored nor endorsed by the Foxboro Company. All postings from this list are the work of list subscribers and no warranty is made or implied as to the accuracy of any information disseminated through this medium. By subscribing to this list you agree to hold the list sponsor(s) blameless for any and all mishaps which might occur due to your application of information received from this mailing list. To be removed from this list, send mail to [EMAIL PROTECTED] with unsubscribe foxboro in the Subject. Or, send any mail to [EMAIL PROTECTED]
RE: Rolling average
Here's a way to do it using a TIMER and an IND block. You could do without
the timer and just use the WAIT for the period but then you might run into
problems if your CP goes into overrun.
This is set for a flow but will work on anything..
INDEPENDENT_SEQUENCE{***
** **
** INDEPENDENT SEQUENCE **
** CONTROL BLOCK**
** **
*}
CONSTANTS {*
* specify any Constants *
* in the following format: *
**
* 12_char_name = value ; *
*}
VARIABLES {*
* specify any Block Local Variables *
* in the following format: *
**
* 12_char_name [ , 12_char_name ] : type;*
**
*where type is one of B, I, R, S, S12, S6*
*}
AVG:R[360];
ICT:I;
USER_LABELS{
* specify any user labeled parameters*
* in one of the following formats: *
**
* 10_char_name : BI00nn; n = 01 -- 24 *
* 10_char_name : BO00nn; n = 01 -- 16 *
* 10_char_name : BA000n; n = 1 -- 4 *
* 10_char_name : RI00nn; n = 01 -- 15 *
* 10_char_name : RO00nn; n = 01 -- 15 *
* 10_char_name : RA000n; n = 1 -- 2 *
* 10_char_name : II000n; n = 1 -- 8 *
* 10_char_name : IO000n; n = 1 -- 5 *
* 10_char_name : IA0001; *
* 10_char_name : SN00nn; n = 01 -- 10 *
*}
FI3050: RI0001; {MEASURED FLOW}
FA3050: RO0001; {AVERAGE FLOW}
CNTIDX: IO0001; {AVERAGER INDEX}
SUM:RO0002; {TEMPORARY SUM}
TIM:RI0002; {10 SECOND TIMER INPUT}
REMOVE: RO0003; {VALUE TO REMOVE FROM SUM}
BTU:RI0003; {ENTERED VALUE FOR BTU}
BTU_VAL: RO0015; {CALCULATED BTU VALUE FOR CURRENT FLOW}
{*
* Specify any Subroutines*
**
**
* SUBROUTINE name ( formal arguments ) ; *
* VARIABLES subr. local variables ;*
* STATEMENTS*
* ; *
* ENDSUBROUTINE *
*}
{*
* Specify any*
*Standard Block Exception Handlers *
**
**
* BLOCK_EXCEPTION exc_name [ DISABLE ] *
* STATEMENTS*
* ; *
* ENDEXCEPTION *
*}
STATEMENTS{*
* Specify the statements here *
*}
CNTIDX := 1;
AVG := SET_ARRAY(FI3050);
SUM := FI3050 * 360.0;
START_TIMER(::10SECONDS.TIMR1,0.0);
START
REMOVE := AVG[CNTIDX];
AVG[CNTIDX] := FI3050;
SUM := SUM - REMOVE;{REMOVE THE OLD VALUE}
SUM := SUM + AVG[CNTIDX]; {ADD IN THE NEW VALUE}
CNTIDX := CNTIDX + 1;
IF CNTIDX 360 THEN
CNTIDX := 1;
ENDIF;
FA3050 := SUM / 360.0;
{CALCULATE BTU VALUE}
BTU_VAL := FA3050 * BTU;
::10SECONDS.TIMR1V := 0.0;
WAIT 1;
WAIT UNTIL TIM = 10.0;
GOTO START;
ENDSEQUENCE
-Original Message-
From: Steve Rigby [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, September 06, 2000 8:01 AM
To: 'Foxboro DCS Mail List' (E-mail)
Subject: Rolling average
Hi all,
What I would like is a way to calculate the average position of a valve over
the last hour, updated say every minute.
and then available as an input for a block. Any ideas?
Thanks in advance.
Steve Rigby
Air Liquide Industrie BV
Merseyweg 10
3197 KG Botlek-Rotterdam
The Netherlands
Tel: +31(0)181-271131
Fax:+31(0)181-271100
Email:
[EMAIL PROTECTED]
[EMAIL PROTECTED]
RE: Rolling average
I would use an independent sequence block. Run the block once per minute, dump the current value of the point to be averaged into a real array indexed by the minute in the current hour, sum up the values in the array, divide by 60 and you have a rolling hourly average. This will automatically overwrite a value which is over an hour old. You have some details to work out, such as how to handle a bad status on the input, getting the minute in the current hour, how to handle the first hour, initializations, restarts, etc., but it should be pretty straightforward. John Windle The Foxboro Company -Original Message- From: Steve Rigby [SMTP:[EMAIL PROTECTED]] Sent: Wednesday, September 06, 2000 9:01 AM To: 'Foxboro DCS Mail List' (E-mail) Subject: Rolling average Hi all, What I would like is a way to calculate the average position of a valve over the last hour, updated say every minute. and then available as an input for a block. Any ideas? Thanks in advance. Steve Rigby Air Liquide Industrie BV Merseyweg 10 3197 KG Botlek-Rotterdam The Netherlands Tel: +31(0)181-271131 Fax:+31(0)181-271100 Email: [EMAIL PROTECTED] [EMAIL PROTECTED] --- This list is neither sponsored nor endorsed by the Foxboro Company. All postings from this list are the work of list subscribers and no warranty is made or implied as to the accuracy of any information disseminated through this medium. By subscribing to this list you agree to hold the list sponsor(s) blameless for any and all mishaps which might occur due to your application of information received from this mailing list. To be removed from this list, send mail to [EMAIL PROTECTED] with unsubscribe foxboro in the Subject. Or, send any mail to [EMAIL PROTECTED] --- This list is neither sponsored nor endorsed by the Foxboro Company. All postings from this list are the work of list subscribers and no warranty is made or implied as to the accuracy of any information disseminated through this medium. By subscribing to this list you agree to hold the list sponsor(s) blameless for any and all mishaps which might occur due to your application of information received from this mailing list. To be removed from this list, send mail to [EMAIL PROTECTED] with unsubscribe foxboro in the Subject. Or, send any mail to [EMAIL PROTECTED]
RE: Rolling average
This may be overly simplistic, but what about using a filter in an AIN block or an LLAG block? A low pass filter really isn't mathematically the same as a rolling average, but for a lot of the applications where the process engineers thought they needed a rolling average, we've found that it's close enough. You'd either need to do the math to calculate the filter time or experiment until you get a satisfactory value. You could set the PERIOD to obtain the desired sampling time. Valve position (or anything else where you don't need accuracy to the nth digit) would seem to be a good candidate for a filtered value. -Original Message- From: Steve Rigby [mailto:[EMAIL PROTECTED]] Sent: Wednesday, September 06, 2000 8:01 AM To: 'Foxboro DCS Mail List' (E-mail) Subject: Rolling average Hi all, What I would like is a way to calculate the average position of a valve over the last hour, updated say every minute. and then available as an input for a block. Any ideas? Thanks in advance. Steve Rigby Air Liquide Industrie BV Merseyweg 10 3197 KG Botlek-Rotterdam The Netherlands Tel: +31(0)181-271131 Fax:+31(0)181-271100 Email: [EMAIL PROTECTED] [EMAIL PROTECTED] --- This list is neither sponsored nor endorsed by the Foxboro Company. All postings from this list are the work of list subscribers and no warranty is made or implied as to the accuracy of any information disseminated through this medium. By subscribing to this list you agree to hold the list sponsor(s) blameless for any and all mishaps which might occur due to your application of information received from this mailing list. To be removed from this list, send mail to [EMAIL PROTECTED] with unsubscribe foxboro in the Subject. Or, send any mail to [EMAIL PROTECTED]
AB KF2 at 19.2 Kbaud?
I have noticed that most of the Allen-Bradley KF2 modules I come across in the field are running at 9600 baud. I also know of some instances where a Foxboro Integrator 30 is communicating with AB KF2s at 19.2 Kbaud. Is there any reason not to run the baud rate at 19.2K? You sure get a lot more I/O throughput that way. Regards, David --- This list is neither sponsored nor endorsed by the Foxboro Company. All postings from this list are the work of list subscribers and no warranty is made or implied as to the accuracy of any information disseminated through this medium. By subscribing to this list you agree to hold the list sponsor(s) blameless for any and all mishaps which might occur due to your application of information received from this mailing list. To be removed from this list, send mail to [EMAIL PROTECTED] with unsubscribe foxboro in the Subject. Or, send any mail to [EMAIL PROTECTED]
RE: Rolling average
My personal favorite is: 1) Build a DTIME block and set the duration to the time period of interest * 1.2. 2) Take the 8 most recent bucket outputs of the DTIME block to the inputs of a SSEL block 3) Set the SSEL block to average its inputs. This approach is kind of cool because: 1) It requires no coding 2) It is pretty darn easy to build 3) It deals intelligently with bad inputs. Remember my Implementation Rules: 1) Do it in regulatory control blocks. (most efficient; least prone to problems) 2) If the regulatory control blocks can't do it, use a CALC block. (efficient, but must deal with BAD and coding errors; debuging is a pain) 3) If the CALC block can't do it, use a Sequence Block (pretty inefficient, but in the CP. Code/compilation relatively complex. Debugging is a pain.) 4) If you can't do it in a sequence block, reconsider if you need to do it. 5) If you must do it, see if you can do it in a shell (sh, ksh, csh, perl, etc.) script (easier to debug, easy to schedule, remember to use omgetimp and omsetimp to avoid broadcasts, remember to use show_params to check the IMPORT table) 6) If you can't do it in a script, reconsider doing it. 7) If you must do it, see if there is a 3rd party or Foxboro package that will do it. (Ask on the mailing list.) 8) If you must do it and can't find a package, write a program. Regards, Alex Johnson The Foxboro Company 10707 Haddington Houston, TX 77043 713.722.2859 (v) 713.722.2700 (sb) 713.932.0222 (f) [EMAIL PROTECTED] mailto:[EMAIL PROTECTED] -Original Message- From: Steve Rigby [SMTP:[EMAIL PROTECTED]] Sent: Wednesday, September 06, 2000 8:01 AM To: 'Foxboro DCS Mail List' (E-mail) Subject:Rolling average Hi all, What I would like is a way to calculate the average position of a valve over the last hour, updated say every minute. and then available as an input for a block. Any ideas? Thanks in advance. Steve Rigby Air Liquide Industrie BV Merseyweg 10 3197 KG Botlek-Rotterdam The Netherlands Tel: +31(0)181-271131 Fax:+31(0)181-271100 Email: [EMAIL PROTECTED] [EMAIL PROTECTED] --- This list is neither sponsored nor endorsed by the Foxboro Company. All postings from this list are the work of list subscribers and no warranty is made or implied as to the accuracy of any information disseminated through this medium. By subscribing to this list you agree to hold the list sponsor(s) blameless for any and all mishaps which might occur due to your application of information received from this mailing list. To be removed from this list, send mail to [EMAIL PROTECTED] with unsubscribe foxboro in the Subject. Or, send any mail to [EMAIL PROTECTED] --- This list is neither sponsored nor endorsed by the Foxboro Company. All postings from this list are the work of list subscribers and no warranty is made or implied as to the accuracy of any information disseminated through this medium. By subscribing to this list you agree to hold the list sponsor(s) blameless for any and all mishaps which might occur due to your application of information received from this mailing list. To be removed from this list, send mail to [EMAIL PROTECTED] with unsubscribe foxboro in the Subject. Or, send any mail to [EMAIL PROTECTED]
Re: AB KF2 at 19.2 Kbaud?
From our in house AB guru: I do not know of a situation in which it wouldn't work at 19.2K, but the bandwidth requirement is small: the bottleneck is the GP, not the DF1 line. If he's actually getting real empirical results back showing a huge ==x2 improvement when moving the DF1 connection from 9600 to 19.2K, then I'd be both surprised and suspecting his ABSCAN and compound configuration. and from our local rep: First, let's clear up any potential confusion. 1770-KF2 - Stand alone box w/ 120VAC power (from outlet) that converts DH+ messages to RS-232C DF1 messages for communicating with the Foxboro. 1785-KE - PLC slide-in module that does the exact same thing. (It fits in a 1771 I/O chassis). The 1770-KF2 does NOT have an option for communicating at 19.2K The 1785-KE DOES let you go 19.2K. Other than that, they are the same beast. The only (potential) draw back to going to 19.2K baud on a 1785-KE module is the baud rate is less noise resistant. It does work, though, and I have little or no problems with it handling that (blazing?!?!) speed! You shouldn't see any problems in your installations, since you guy's typically use well shielded cable for your serial interfaces. Kirk, I know you have a lot of KE modules out there, but I do think you are using some KF2 modules also, although I don't know where. The Foxboro, or any DCS, can not tell the difference between the two, since they're are basically the same thing, only in a different housing. Kirk Carver ExxonMobil Chemical Beaumont Polyethylene Plant PO Box 2295 Beaumont, Texas 77704 Phone: 409-860-1314 [EMAIL PROTECTED] - David Johnson [EMAIL PROTECTED] on 09/06/2000 09:32:08 AM Please respond to Foxboro DCS Mail List [EMAIL PROTECTED] To: [EMAIL PROTECTED] cc:(bcc: Kirk D Carver/Beaumont/Mobil-Notes) Subject: AB KF2 at 19.2 Kbaud? I have noticed that most of the Allen-Bradley KF2 modules I come across in the field are running at 9600 baud. I also know of some instances where a Foxboro Integrator 30 is communicating with AB KF2s at 19.2 Kbaud. Is there any reason not to run the baud rate at 19.2K? You sure get a lot more I/O throughput that way. Regards, David --- This list is neither sponsored nor endorsed by the Foxboro Company. All postings from this list are the work of list subscribers and no warranty is made or implied as to the accuracy of any information disseminated through this medium. By subscribing to this list you agree to hold the list sponsor(s) blameless for any and all mishaps which might occur due to your application of information received from this mailing list. To be removed from this list, send mail to [EMAIL PROTECTED] with unsubscribe foxboro in the Subject. Or, send any mail to [EMAIL PROTECTED] --- This list is neither sponsored nor endorsed by the Foxboro Company. All postings from this list are the work of list subscribers and no warranty is made or implied as to the accuracy of any information disseminated through this medium. By subscribing to this list you agree to hold the list sponsor(s) blameless for any and all mishaps which might occur due to your application of information received from this mailing list. To be removed from this list, send mail to [EMAIL PROTECTED] with unsubscribe foxboro in the Subject. Or, send any mail to [EMAIL PROTECTED]
