question about comments

[plcdp 11]

Hello, I was wondering, if I make a couple of blocks of memory available to store comments, does that slow the program execution time (scan time) down? Thanks, plcdp

[Veganic 8]

No.

[plcdp 11]

Thank you. plcdp

[Goody 5]

The trouble with downloading comments with the program is - (unless I have missed something) it all seems a bit had-hoc. Don't get me wrong, comments residing within the plc has always been a great plus for mitsubishi. Not many other manufacturers do this and it is a great help to upload an unknown program and get the comments with it too. But there doesnt seem to be any method to it - or any way of defining which comments are saved. My normal modus operandi is to wait until I have virtually finished the program, then use the spare memory for the comments. Depending on the model and size of program - the spare memory can be large or small but it's guesswork which ones will be saved. In my opinion, it would be great if you could define that M relay comments are saved before I/O - because inputs and outputs can be traced whereas M relays and timers etc are not always obvious as to what they do.

[kaare_t 155]

OR: If someone at Mitsu (or other brands) would actually sit down and give it just a tiny, tiny, tiny thought they might find out that memory is cheap today , so why not just put in a small dedicated memory for comments, and always save everything ..... It would probably increase the price by 0.00001% Never understood the "logic" regarding this , so if someone have a good "answer" let us know

[Crossbow 295]

Or why not use the newer products which already ahve tons of memory? FX1N (8K) was replaced by FX3G (32k), FX2N (8/16k) was replaced by FX3U (64k), and Q offers up to 260k of program memory. Which software are you using? Which PLC? You can tell the download which comments to include in GX Developer. On the Write To PLC dialog, there are tabs. On the Common tab you can set the ranges of comments to download.

[kaare_t 155]

Yes this is of course correct Crossbow (regarding both new CPU's and "select" options), however my point was simply how easy it would be to have a dedicated "comments" memory. If you have a big program, why should you have to exclude comments in the download? You could say that: 1. Don't download comments 2. Just download some of the comments 3. If you have a FX, buy a Q. 4. If you have a full Q, then put in another one (to a total of 2/3/4 CPUs) and so on.... All in all, I don't feel that this is a problem, but as I first said; the solution is so easy and cheap and I cannot see why they haven't implemented this many years ago (and still don't implement it)

[Goody 5]

Lol, well beggar me. been doing this years and I never knew that! I shall do a little testing to see how this works. I did say 'unless I missed something' :) because I'm famous for missing the obvious.

[Crossbow 295]

I agree more memory dedicated for comments would solve this. But Mitsubishi is into backward compatibility. So it's done the same way in the FX3U it was done in the FX2N it was done in the FX.