dimmitrisd

ahahahaha!thanks a lot for the advice!i 'll keep it in mind :)

thanks man.that was an explanation i really needed. i found my way anyway.i got a new copy of step 7 v5.5+sp1 included and after i installed it (windows 7 professional) i can also see that i got a trial license installed.so i assume that it will be ok for me to experiment with this in my pc. Νow when trial will be over (have no idea when!!!) we'll see....my case is that i am only familiar with schneider products and i'm newbie into it!!!!! :) thank you very much.

Thanks Rodney. Probably Siemens Micro Win S7-200 could help me, as it says that it supports Win XP nad higher, but as long as I can see, there is nowhere a "download" button or link in the page you've attached me. Are you sure someone can download a trial of that?

:) dear boblfoot thanks very much.ive already seen these posts in siemens site,but I think that versions mentioned over there are not for Win 7. that's why i turned my questions to you.have i understood it wrong??? sorry for insisting ;)

i got confused with siemens site.perhaps because it's the first time i'm getting involved with siemens.:) please,does anyone know if there is available "any" step 7 version for windows 7 home or professional for TRIAL use???? i'm trying to find it on site but I cannot!!!!""

Hallo my friend! I wonder whether you found a sollution to your problem!? You know, I've made a connection like yours (two modicon M340 plc's communicating each other with modbus read_var etc) but I don't ever cancel modbus master with cancel bit or with some other way. I have no problem till now. If i don't ever cancel the read_var but always read_var asks, do you think that if a slave has some problem replying, I will also have a problem with my master? Have you had such a problem? Now you made me wonder!!!!