comparing strings in s7-315

notfish

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• Apr 1, 2003

• #1

can anyone tell me how to compare strings that store in DBs?thanks

 

seppoalanen

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• Apr 1, 2003

• #2

How len string(s)?

 

notfish

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• Apr 1, 2003

• #3

it's string[8].i wanna output fault messages,and when the problem solved,clear the message that stored in db.but i don't know how to identify the one i need to clear if string[] can't be compared in s7.it seems that step7 havn't comparision instructions for string type,only for int,d-int,float.

 

RGB

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• Apr 1, 2003

• #4

In the standard library there's a folder of IEC FCs and FBs. There's a string compare block in there, I'm pretty sure it's FC10.

 

notfish

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• Apr 1, 2003

• #5

hi,RGB.thanks for helping!but it defined string[254],and what i need is string[8].can this be solved?

 

jvdcande

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• Apr 1, 2003

• #6

It states STRING[254] because that's the maximum allowed stringlength. Just put your STRING[8] values to the parameters of FC10 and it should work fine! If you put a short string into a long one there's no problem, if you put a long string into a short one, its 'tail' is removed.

Kind regards,

Jean Pierre Vandecandelaere

 

notfish

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• Apr 1, 2003

• #7

thank you!it work