Do you know if it's enough 7 minutes to transfer from platform 11 to platform 17 in Nagoya station?

I suspect that you are travelling from Expo to Kyoto.

The transfer means walking down a flight of stairs, going down a walkway and then walking/riding an escalator up (or walking up stairs). If you send your bags ahead, then no problem. If you can carry your bag down the stairs and back up then no problem.

The following webpage has maps of some of the JR stations, including Nagoya:
http://jr-central.co.jp/english.nsf/doc/maps

On the left side of the map is the "North Walkway". You can see on the right side of the walkway there is a stairway to/from platform 11. On the left side of the walkway is an escalator, probably going up, to platform 11.

You get off the train onto platform 11 and follow the crowd downstairs. Follow the shinkansen signs. You will show your JR Pass at the Taiko Dori North Ticket Gate to get to the shinkansen tracks.

Down at track 17, the blue platform on the map, you can see that there are side-by-side stairways and escalators on both sides of the North Walkway.

You can board any car and walk between cars to get to your seats, but you should still have a couple of minutes to find and board the correct car.

By comparison, about a week ago I made the transfer between track 22 to 20 at Shin Osaka station. It was listed as a 3 minute connection. I boarded the car closest to the escalator, saw it was packed and decided to get out and walk the lenght of the car down the platform to the next car. Halfway through that car the doors closed and the train departed.

I didn't look at the Shinjuku map last night when I answered your question about connecting there because the trains between Ikebukuro and Shinjuku are frequent. So, it was easy to advise taking a slightly earlier train.

Links to major JR East stations, including Shinjuku station are here:
http://www.jreast.co.jp/e/estation/index.html

You can see that the JR Saikyo Line from Ikebukuro uses the two platforms for tracks 1 to 4 and that the train to Matsumoto is at the platform for tracks 5 and 6. (note that the Yamanote Line, another option for getting to Shinjuku, is some distance away at track 13).

Under the same conditions as the Nagoya transfer (no bags or carrying your bag down/up stairs), then your original itinerary of taking 6 minutes to connect at Shinjuku would give you enough time. Doesn't hurt to take the 9 min earlier train, though.

thank you very much again for your help. It's between Nagiso and Nagoya.

That doesn't make sense. According to the map track 11 is used by the Kansai main line. From Nagiso you would be on the Chuo main line Nagoya. If you are using hyperdia, then what is your departure time from Nagiso? Your destination obviously is not Nagoya because track 17 is for the shinkansen bound for Shin Osaka.

Our destination is Hiroshima but we have to go to ShinOSAKA because we can't go into Nozomi. And in hyperdia I've read the train arrives at 9.17(departure time from Nagiso 08.09)

ok, thanks. then there is a discrepancy between hyperdia (which says platform 11 for Kansai main line) and the platform guide on the JR Central map (which says 7,8,10 for Chuo line). I am p.d. sure that the Kiso Valley trains like the Shinano LEX run on the Chuo Honsen (central main line) and the Kansai Honsen runs between Nagoya and JR Namba station. Ok, so I'm becoming a JR geek.