S7-200 converting to MicroLogix

chenley

Member
Join Date
Feb 2010
Location
West KY
Posts
9
We have a simple pallet wrapper that we are trying to convert from a S7-200 to a MicroLogix 1400. Out of 119 rungs we're getting stuck on converting two of them (attached).

Everything else appears to be working correctly. Except these two rungs I believe control the number of wraps. Not sure what the Allen-Bradley instructions would equal the Siemens instructions. The MUL is pretty self-explanatory, although not sure about the WAND_W and SHR_W.

NET61.jpg NET62.jpg
 
The WAND_W is a word 'AND' the two words on the input to instruction are bit for bit AND'ed, and the result is on the output of the instruction.


The SHR_W is a word shift right. the input word is shifted right bit for bit.


Steve
 
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Where is the IW0 coming from and the VD8 (Network 61) and VD12 (Network 62) going to? Using the cross-reference IW0 seems to come out of nowhere and VD8 and VD12 only show up on those two lines.

This is my second time in my life looking at a S7 program. All our equipment is A-B based and using cross-reference seems a tad bit different between the two.

Edit: A little more research, I assume IW0 is coming from all the inputs from 0.X? Still can't find much on the VD8/VD12 part except that it is "internal variable memory".
 
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Where is the IW0 coming from and the VD8 (Network 61) and VD12 (Network 62) going to? Using the cross-reference IW0 seems to come out of nowhere and VD8 and VD12 only show up on those two lines.

This is my second time in my life looking at a S7 program. All our equipment is A-B based and using cross-reference seems a tad bit different between the two.

Edit: A little more research, I assume IW0 is coming from all the inputs from 0.X? Still can't find much on the VD8/VD12 part except that it is "internal variable memory".

Fair warning: I haven't used the S7 200's much, they are a bit different from the bigger brothers I'm more familiar with.

Yes, IW0 probably refers to the bits I0.0-I1.7.

I'm not sure about the V memory. It might be tied to some wizards in the project, possibly communications?
 
VB = 8 bits internal memory
VW is a 16bits memo
VD is a 32bits memo

All of them use the same memory map so
(VB0,VB1,VB2,VB3) = (VW0,VW2) = VD0
next adresse in a row after VD0 you get VD4 because a VD use 4 bytes of memory

WAND is a ''AND'' logic of each bit of the word
SHR is a ''shift right'' operation of the number of defined bit at the ''N''

For more info you may look at that manual
http://www1.siemens.cz/ad/current/c...stemy/simatic_s7200/manual_s7_200_2005_en.pdf

Is it blown or you just want it to be AB ?
 
The S7-200 is still good, only having issues with the wrapper arm returning to "home" position, which is determined by a sensor being flagged. 25% of the time, when the wrapper arm is suppose to return "home" it stops 180° out.

Have been troubleshooting it and with our limited knowledge of Siemens logic, figured while troubleshooting it might as well update it to a MicroLogix. Two reasons: 1) The microWin software dosen't seem to like Win7 or Win10. 2) This is the only piece of equipment we have with a Siemens PLC.

Does help greatly knowing that VB0, VW0 and VD0 are all the same, have been looking at it as though they were completely different memory allocations. Looks like I've got more tracing down to do knowing that now. Figuring these two rungs are being used as a sequencer for how the I/O operates.

Thank you greatly for the help thus far.
 

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