How to determine how many bits some specific DB is containing

naturephoenix

Member
N
Join Date
Jan 2015
Location
Vienn
Posts
181
I got some function which is looping some shared DB, input variable is number of bits...but is there any way to find out number of bits inside specific DB
 
I am trying to get how many set bits is inside the DB, but its not working
LAR2 P#DBX 0.0
OPN "Alarmi"
L DBLG
L 8
*I

Lp: T #LoopSize
A [AR2,P#0.0]
JC inc
JU end
inc: L "Tag1".Alarm_count
L 1
+I
T "Tag1".Alarm_count


end: +AR2 P#0.1
L #LoopSize
LOOP Lp

Whats wrong over here?
 
Try this: (Note: pointer value is not shifted with shl 3 or multipled with number 8 now, because we want also look bit pattern (dbx x.0 .. x.7)




      OPN   DB100

      L     DBLG

      T     MD    30           // db-area lengt (bytes)



      L     MD    30

      L     8

      *I    

      T     MD    34           // db-area lengt (bits)



      L     L#0                // zero for bit_pointer

      T     MD    38           // and   bit_nmb_conter 

      T     MD    42







a001: A     DBX [MD 38]       // check bit value

      =     M     50.0        // only for testing

      JNB   a002

      L     MD    42          // if bit=1 -> count up 

      L     1

      +I    

      T     MD    42



a002: L     MD    38         // bit checked/counted up 

      L     1

      +I                     // check next bit (pointer +1)

      T     MD    38        



      L     MD    38

      L     MD    34         //loop back, if db-area not

                             //fully checked

      >=I   



      JNB   a001





      NOP   0

 
naturephoenix said:
I am trying to get how many set bits is inside the DB, but its not working
LAR2 P#DBX 0.0
OPN "Alarmi"
L DBLG
L 8
*I

Lp: T #LoopSize
A [AR2,P#0.0]
JC inc
JU end
inc: L "Tag1".Alarm_count
L 1
+I
T "Tag1".Alarm_count


end: +AR2 P#0.1
L #LoopSize
LOOP Lp

Whats wrong over here?
Click to expand...


Looks like that you need only need zero alarm_count before looping, now alarm counter will keep adding from old counted value, when db-block is checked and new checkin is started:

LAR2 P#DBX 0.0
L 0
T "Tag1".Alarm_count
OPN "Alarmi"
L DBLG
L 8
*I

Lp: T #LoopSize
 
I always got Alarm_count is equal to 1 no matter how many bits is SET
Once they all are equal to false Alarm_Count becomes equal to 0

L "Tag1".Alarm_count
T "Tag1".Alarm_count_history

//

LAR2 P#DBX 0.0

L 0
T "Tag1".Alarm_count

OPN "Alarmi"
L DBLG
L 8
*I

Lp: T #LoopSize
SET
A [AR2,P#0.0]
JCN end

L "Tag1".Alarm_count
L 1
+I
T "Tag1".Alarm_count


end: +AR2 P#0.1
L #LoopSize
LOOP Lp
L "Tag1".Alarm_count
T MW 100


Mistake is somewhere here "A [AR2,P#0.0],+AR2 P#0.1"
I think at least
 
There is no mistake in your code as posted, here it is being used with a DB containing 3 bits that are true. Post the code you are running in an archived library as an attachment.

ac.JPG
 
naturephoenix said:
I always got Alarm_count is equal to 1 no matter how many bits is SET
Once they all are equal to false Alarm_Count becomes equal to 0

L "Tag1".Alarm_count
T "Tag1".Alarm_count_history

//

LAR2 P#DBX 0.0

L 0
T "Tag1".Alarm_count

OPN "Alarmi"
L DBLG
L 8
*I

Lp: T #LoopSize
SET
A [AR2,P#0.0]
JCN end

L "Tag1".Alarm_count
L 1
+I
T "Tag1".Alarm_count


end: +AR2 P#0.1
L #LoopSize
LOOP Lp
L "Tag1".Alarm_count
T MW 100


Mistake is somewhere here "A [AR2,P#0.0],+AR2 P#0.1"
I think at least
Click to expand...

Do you use FC or FB block for this? (if there is any difference, but FB blocks uses AR2 also deeply inside)
 
if I use datablock area for loopsize and alarmcount directly on loop, I get for some reasons area lenght errors.

But if I use memory marker area (MW) first and afterwards copy markers to db-area then PLC don't give area lengt errors
(I runned code at simulator, maybe some limits there with indirect addressing???)
 
L D[AR2 said:
There is no mistake in your code as posted, here it is being used with a DB containing 3 bits that are true. Post the code you are running in an archived library as an attachment.
Click to expand...

Oops, yes there is a coding error:

Code: 
OPN   "Alarmi"
      L     DBLG
      L     8
      *I    

Lp:   T     #LoopSize
      [COLOR=Red][B]OPN   "Alarmi"[/B][/COLOR] //this instruction required.
      SET   
      A      [AR2,P#0.0]
      JCN   end

      L     "Tag1".Alarm_count
 
L D[AR2 said:
Oops, yes there is a coding error:

Code: 
OPN   "Alarmi"
      L     DBLG
      L     8
      *I    

Lp:   T     #LoopSize
      [COLOR=Red][B]OPN   "Alarmi"[/B][/COLOR] //this instruction required.
      SET   
      A      [AR2,P#0.0]
      JCN   end

      L     "Tag1".Alarm_count
Click to expand...


why there is Set-command before A [AR2,P#0.0]?
 

Similar Topics

M
How to determine the direction of a moving object with 2 sensor inputs
Hello, i am a beginner with a Siemens Logo 8 PLC. I would determine the direction of an object if it passes a whole cycle of 2 input sensors. See...
Replies
2
Views
181
drbitboy
drbitboy
A
CIP Motion Axis - determine actual direction of motion
Hi all, Just looking through the CIP_AXIS_DRIVE data type in a Logix controller to look for something that can tell me whether the current...
Replies
2
Views
1,065
JeremyM
JeremyM
B
Logix5000: Able to programmatically determine tag name -> STRING
I'm currently working on an MES interface PLC which passes around a whole bunch of strings. A lot of these strings are really just to allow for an...
Replies
0
Views
1,115
bevanweiss
B
the_msp
Determine AB firmware
I don't use AB much these days, and any installs I've done in years past have been setup by myself from scratch, so I've always known what...
Replies
8
Views
2,082
dmroeder
dmroeder
A
How to determine a Logix processor load
Hello: I wonder if there is a way to find the CPU load of a Logix processor, and if it is not possible to determine this in an absolute way, I...
Replies
6
Views
1,996
JeremyM
JeremyM
Back
Top Bottom