Hello,

first of all Im a self learner,

Im confused with microwin/s7 200 shift register programing.

my intention is

1. define a variable V0

2.shift left V0 if input bit I0.0 

3.set Q0.0 according to V0.8 high or low

please help to understand.

Chandana

Hello,

first of all Im a self learner,

Im confused with microwin/s7 200 shift register programing.

my intention is

1. define a variable V0

2.shift left V0 if input bit I0.0 

3.set Q0.0 according to V0.8 high or low

please help to understand.

 Hi.

I think I understand what the source of your problem is. Please review the program attached with this post. (Please do not mind the custom colouring of the program.)

There are a few brands of PLC which I can think of that you may be thinking of, while doing this program. Those behave like 16-bit processors.. Siemens PLCs behave like 8-bit processors.

In Siemens CPUs: WORD sized variables are constructed from x2 BYTES and each BYTE has 8 bits. The numbering of the BYTES in the WORD is left to right, while bits are numbered right to left. (very confusing.. I know.)

Therefore VW0 is built up by VB0 (left, most significant byte) and VB1 (right, least significant byte). In turn VB1 has bits V1.0 (right, least significant bit) to V1.7.

If you can wrap your head around this all, then you will do just fine. Please know that the HELP in Microwin is of the best constructed help files I have ever seen for PLC software - please have a look at it again with the new knowledge.

Helpful?
w

Dear william

it is very helpfull. thanks in advance