Re: [foxboro] a simple challenge


Michael,

If I understand correctly you want to trigger a series of solenoid valves
in sequence every X seconds.  Each solenoid valve to stay open for Y
seconds, with the next solenoid valve in sequence to open as the prior one
closes.

I'd probably do the logic in a CALCA or CALC block.  Something like this
ought to work.  BO01 - 4 are outputs to drive solenoids.  I'd just use COUT
blocks or an MCOUT connected to BO01-4 to drive simple solenoids.

type = CALCA
period = 2 (execute each second)
ii01 = seconds between cycle repeats
ii02 = seconds for each solenoid
timini = 1 (so OSPs don't trigger on initialize)

1  in ii02
2  stm m01   ; store SV on time in mem for osp
3  inc io01
4  in io01   ;
5  in ii01   ;
6  sub
7  bip 11    ; on new cycle go to init
8  clr bo05  ; otherwise clear cycle flag
9  gto 13    ; and skip initialize
10 clr io01  ; initialize second counter
11 set bo05  ; set in cycle flag
12
13 in bo05   ; on bo01 to 1
14 osp m01   ; generate signal for SV 1
15 out bo01
16 in ~bo01  ; on SV1 finish
17 osp m01   ; generate signal for SV 2
18 out bo02  ;
19 in ~bo02  ; on SV2 finish
20 osp m01   ; generate signal for SV 3
21 out bo03  ;
22 in ~bo03  ; on SV3 finish
23 osp m01   ; generate signal for SV 4
24 out bo04
25 end
27

Regards,

Kevin FitzGerrell
Systems Engineer
Foxboro New Zealand
------------------------------------
Tel:  +64 (9) 573 7690
Fax:  +64 (9) 573 7691


                                                                                
                                                     
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                    11/21/01 08:24 PM                                           
                                                     
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Hi list,

We are going to replace a local relay / timer driven filter cleaning
sequence by "something" in I/A.
We therefore need to separately activate 4 solenoids, one after the oth=
er,
for a variable number of seconds (most likely 2). The interval between
activating the solenoids should also be variable.
I have already made something with a Calc block that generates seconds =
( 0
to 62) connected to a AIN block. On the four boolean alarm limits I
connected the solenoids using a GDEV with the pulse option on. But ther=
e
must be something more brilliant than this, without the use of a DEP bl=
ock.
The solenoids will be connected (2?wire) to FBM41C/42C, therefore a PLB=

solution is an option.
All suggestions are more than welcome.

thanks,

Michel




Michel van den Berg
PFW Aroma Chemicals B.V.
PO Box 415
3770 AK Barneveld
the Netherlands

Phone : (31)342 - 407 791
Fax   : (31)342 - 407 789
email : mvandenberg@xxxxxx
FedEx : Nijverheidsweg 60
        3771 ME Barneveld
        the Netherlands





 
 
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