Step 7 - how to monitor strings

[panic mode]

hi everyone,

is there a better way to display strings in S7? there is a piece of code that depending on program status copies one or another string to given memory location which is read by customer's system. the problem is that i have no way of displaying this in Step7.

i can for example insert block of characters in VAT but only first 10-15 of them will ever be displayed, the rest is never refreshed. another problem is that this is just one of the few output messages. i would like to monitor all of them. so far monitoring just one is nothing but pain. any ideas?

regards

panic mode

 

[L D[AR2P#0.0]]

I copy each string to an array of chars in a DB and monitor the DB

 

[Manglemender]

Hmmm... Yes strings are a pain to monitor. The only satisfactory way I've found of doing it is to write yourself a dummy HMI in WinCCFlexible, add the strings as tags and put them on a page. Start it up in runtime to monitor your strings that way.

Nick

 

[Bratt]

If you open the data block online or switch from offline/online you can see the current string. The string will not update you can only see the string from the moment you opened the data block but its enough sometimes.

 

[panic mode]

hi everyone and thank you for replies

I copy each string to an array of chars in a DB and monitor the DB

i did try monitoring DBs and this is also not working. only very begin of the DB is refreshed (first 20-30 bytes of the DB, regardless of content), once you scroll further down, you are on your own. for some reason they seem to always refresh the block from begin, regardless what part of the DB is viewed. it should refresh only what is on screen, but that's not how it works. when monitoring DB, it is unlikely to see anything even on second page and there is no chance of having anything monitored further down.

then i tried to display it in VAT, same problem, only 20-30 bytes are refreshed so one has to keep inserting and deleting monitored characters.

then i tried to copy them to a temp DB (so that they are on the top) and monitor - same results. but this was also string, not an array of chars. i will try it soon but given perious experience, i don't expect this to be any different than strings (VAT was showing array of chars but only 1/4 of one string was ever displayed).

Hmmm... Yes strings are a pain to monitor. The only satisfactory way I've found of doing it is to write yourself a dummy HMI in WinCCFlexible, add the strings as tags and put them on a page. Start it up in runtime to monitor your strings that way.

this is exactly what I did eventually - after struggling with Step7 for more than half an hour:

the problem is that i have no way of displaying this in Step7.

the only problems are:
- one must have WinCC flexible (which I did)
- it takes some time to set this up (AFTER wincc is finally started)

in my case this was on a project i was not exactly familiar with (if it was me, i would put those on HMI in the first place).