shift register

hey all 

if you have any idea regarding with shift register please tell me what about shift register...how do you program a shift register with the LAD/FBD statements in STEP7 V5.5 and STEP7 (TIA-PORTAL)

with regards

ted

thanks Piotr.M 

it is not possible at LAD or FBD?

Piotr.M

S7-300/400 - You will need use STL to do it

there are following bit shift instructions

SLW, SLD - shift left word (16bit) / dword (32bit)

SRW, SRD - shift right word (16bit) / dword (32bit)

RLD, RRD - rotate Left/Right Double Word

in case of shift instructions you can add number of bits, no number of bits = shift by one bit.

The empty position is filled with 0 and bit which is shifted out is written into status word bit CC1 which can be examined by instruction JP (jumps when shifted out bit=1)

There's also the RLDA in the STL. Quite usefull if one'd like to have an bit SR longer than 32bits without excessive coding CC1 checks.

But all mentioned instructions (excluding the RLDA) have their counterpart in the LAD/FBD, so why one need use the STL for that?

Also CC1 can be examined in LAD/FBD.

ted.atman

it is not possible at LAD or FBD?

Of course it's possible. At least to some extent. But the first question is what kind of an SR you need? Or what you want to shift with it, i.e. how a single piece of your data looks like and how many pieces you have?