6-bit current format to real

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Join Date
Jul 2006
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mimon
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Hi, everybody

Do you know anybody function in Step7 for convert 6-bit curret format to real, thanks
CurretFormat_Step7.jpg
​
​

​

 
I don't know of any ready-made function. But math behind presented diagram seems to be pretty simple (or I missed something :D ).

L your_data //load it to ACCU
ITD //treat it as a int and convert to dint
DTR //dint convert to real
L 32.0 //load constant
/R //divide as reals
T some_real_variable //store wherever you like
 
Last edited:
Where did you find those 6-bit, 8-bit and 9-bit current formats ?
What module type is it exactly ?
For siemens S7-300/400, the analog modules (almost) always scale from 0 to 27648.
 
thanks, its very easy

icon7.gif


jacekd said:
I don't know of any ready-made function. But math behind presented diagram seems to be pretty simple (or I missed something :D ).

L your_data //load it to ACCU
ITD //treat it as a int and convert to dint
DTR //dint convert to real
L 32.0 //load constant
/R //divide as reals
T some_real_variable //store wherever you like
Click to expand...
 
its profibus communation module for softstarter Sirius 3RW44



JesperMP said:
Where did you find those 6-bit, 8-bit and 9-bit current formats ?
What module type is it exactly ?
For siemens S7-300/400, the analog modules (almost) always scale from 0 to 27648.
Click to expand...
 
I'm trying to do the same thing.

The 2 input BYTES from the softstarter, got I address 10 and 11 in hardware config. I want to read the 6-bit current from the softstarer, bits 11.0 to 11.5, and display it in the OP panel.

Can anyone help me with the instructions?
 
Mask the bits you are not using and move into a integer and you are done.

Assuming your doing this in a FC/FB.

1. Make a Temp Variable Call 6BitINT (note address)
2. AND it with 2#0000 0000 0011 1111 (Don't use space only for reference)
3. Move New Variable which is defined as INT type...your done

I'm not sure you have bit pattern correct but you get the idea.

Nick
 
Try it

L #InputByte // second byte IB11
ITD
DTR
L 3.200000e+001
/R
T #Percentage

L #Percentage
L #MotorCurrent //rated operation current from HW config (parameter assignment)
*R
T #ActualCurrent


pbar
 
Last edited:
OK, I`m not getting this to work. Here is my code while the softstarter is running:

L MB 11 b
ITD b
DTR 41300000
L 32 42000000
/R 3eb00000
T MD 150 3eb00000

L MD 150 3eb00000
L 616 268
*R (no value!)
T MD 154 (no value!)


I'm new to programming. Please help me.
 
Readings in Online mode:

L MB 11 Reading: b
ITD Reading: b
DTR Reading: 41300000
L 32 Reading: 42000000
/R Reading: 3eb00000
T MD 150 Reading: 3eb00000

L MD 150 Reading: 3eb00000
L 616 Reading: 268
*R Reading: (no value!)
T MD 154 Reading: (no value!)
 
Just make screenshots from STEP7.
Make screenshots with all kinds of "representation", decimal, floating point, hex - not automatic.

Anyway, the line that says
L 32
should be changed to
L 32.0

edit:
And the MB11 is really filled with the data from the input byte from the softstarter ?
Why not just use the input byte ?
 
Last edited:
The current being displayed in the OP panel updates too slow.
When the motor is running, the current in the OP panel updates with 20A at the time. The rated motor current is 616A.

How can i get the PLC to update the current more accurate?
S7-315, OP77B
 

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