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I can't place a STRING data in my data block in the STRUCT

Created by: rQx at: 2/18/2011 8:56 AM (11 Replies)

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2/18/2011 8:56 AM	Rate (0)
rQx Bronze Member Joined: 12/9/2010 Last visit: 9/19/2023 Posts: 162 Rating: (4)	So a new problem accured. I'm transfering batch numbers between my CPUs and these consist of Letters and Numbers. I think the correct data type for this is the STRING. Is that correct? If so, my problem is that I can't place a STRING data in my data block in the STRUCT. If I have understood this correctly it is in the STRUCT of my data block I shall place the data to be transfered over the ethernet communication. If I use a second TSND_C and TRVC_C block in my CPUs to transfer the STRING seperatly, is it possible to make them work together so that the information come to the right place. TSND_C 1 to TRCV_C 1 TSND_C 2 to TRCV_C 2 The information in TSND_C 1 shall not be transfered to TRCV 2. Understand my questions? I will be thankfull for any suggestions Regards /Tim Splitted from s7 1200 - s7 1200 ethernet connection Rcv and Send.
	Last edited by: O_Moderator at: 2/21/2011 7:55 AM new subject after splitting
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2/21/2011 10:52 AM	Rate (0)
smiffy Platinum Expert Joined: 1/17/2007 Last visit: 7/28/2023 Posts: 1525 Rating: (527)	A string is just an array of characters, so you could have a character array (ARRAY [1..n] OF CHAR) in your STRUCT and copy the string to it. You will need to do this anyhow, as the string type does not just include your ASCII characters. The first 2 bytes of the string contain the maximum length of the string and the current length of the string. As you don't want to send this data (you only want to send the ASCII data), then you will have to bypass these bytes somehow. So you might as well do it by using a copy and a copy it to your character array in your structure at the same time - killing two birds with one stone. Use the BLKMOV call to do the copy and use indirect addressing / ANY pointer to access the 3rd byte of the string (first ASCII character). If you need any help in doing this, please just ask.
	Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
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2/21/2011 12:45 PM	Rate (0)
rQx Bronze Member Joined: 12/9/2010 Last visit: 9/19/2023 Posts: 162 Rating: (4)	So that's a solution to my problem , I thank you for that and will try to make it work. However I have some thoguths about it. I make a data block called DB, insert a string called Batch. On my TSEND_C DATA input I typ "DB".batch .. Then I can recieve it with my TRCV_C block. A string sent over ethernet , no problem. Why is this not possible when I'm sending a full data block? It seems like this is a strange way of sending strings over ethernet. Surely there must be an easier way? It would all be solved if it's possible to have two pair of TSEND_C and TRCV_C in my PLCs. Is this not possible?

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2/21/2011 2:06 PM	Rate (0)
smiffy Platinum Expert Joined: 1/17/2007 Last visit: 7/28/2023 Posts: 1525 Rating: (527)	There is no technical reason why you should not be able to send an entire datablock. There might be limits to how big a datablock you can send though. What error codes are you getting when you try to send the full datablock?
	Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
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2/21/2011 3:59 PM	Rate (0)
rQx Bronze Member Joined: 12/9/2010 Last visit: 9/19/2023 Posts: 162 Rating: (4)	Well, I create a datablock, then I create a "struct" and when I trie to choose what memory I want to use "Uint" "int" "bool" etc. I try to choose string but it become red. I will do some more testing tomorrow but this is how far I've got. Maybe if I reduce the string to 10characters it will take less space and can be sent. No clue on the two TSEND_C?

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2/21/2011 4:54 PM	Rate (0)
smiffy Platinum Expert Joined: 1/17/2007 Last visit: 7/28/2023 Posts: 1525 Rating: (527)	Did you specify the string size in square brackets after the string definition (e.g. STRING[254])?
	Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
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2/21/2011 11:05 PM	Rate (0)
rQx Bronze Member Joined: 12/9/2010 Last visit: 9/19/2023 Posts: 162 Rating: (4)	No I did not, I just picked string in the meny where I chose the memory type. Maybe I was working to fast, if I specify string and then name[] it will work. Will check first thing in the morning!

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2/22/2011 7:56 AM	Rate (0)
rQx Bronze Member Joined: 12/9/2010 Last visit: 9/19/2023 Posts: 162 Rating: (4)	Ok so I was wrong about the error. The problem is that I can't even select a string data type under the struct. Isn't there any way of having two send blocks send information to two recieve blocks on the other plc? This should solve the problem right away. Also I tried experementing with the char - string convertion. I use the MOVE_BLK I sepcify my char as "db".string.char1 , DB1.DBB0. This becomes red and say "only ARRAY elements can be used here. Further more I have my string in the output"DB".TextString[5], DB1.DBB10. It becomes red and say "Access of elements of data type STRING is not allowed here. However, I find it very strange that I can send a string seperatly over ethernet but not when I send the entire DB.
	Last edited by: rQx at: 2/22/2011 8:57 AM
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2/22/2011 11:20 AM	Rate (0)
smiffy Platinum Expert Joined: 1/17/2007 Last visit: 7/28/2023 Posts: 1525 Rating: (527)	Can you attach your structure so I can have a look please?
	Last edited by: smiffy at: 2/22/2011 11:20 AM Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
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2/23/2011 6:02 PM	Rate (0)
rQx Bronze Member Joined: 12/9/2010 Last visit: 9/19/2023 Posts: 162 Rating: (4)	I will do this at work tomorrow, sorry for late reply, I had alot to do today.

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