Move String Data in Ladder Logic S7 Siemens

blacksilver80

Member
Join Date
Mar 2007
Location
MICHIGAN
Posts
14
I am trying to move a String data in Ladder Logic in S7 300.
Do i need a new FC (like FC 2) or is there a separate move command to move a Real String Data in to another Database. Because another machine will fetch the data from my PLC and It can only take it in String Format.
 
Can you be more specific.

Are you trying to move String data from one area to another in the same PLC?

When you say the other system (what is it?) can only read string, are you talking about serial comms here????

What is FC2 (sorry I don't have S7 here with me), is it a standard FC you are talking about?
 
No I am just trying to see If I can move some String data in my own PLC
For example, If a get Part 1 ...I want to move a DATA to a DB Location in STRING format in my own PLC
No need to worry about the other PLC..I just need to get my DB populated with the STRING Data thats all ...need to populate a DB in my plc with data in string format.

FC 2 is String concatenation but i dont if it will work....I still debugging that right now
 
From a manual I see FC2 = CONCAT, combines two strings together.

If you are moving a string, it is probably best to use SFC20 to block move the string data.

You need to clarify your question though.
 
FC31 (REPLACE) could possibly be used for string to string.

But if its a known length of data, I would use SFC20, block move the data from one area to the next.

It can also be achieved by Load and Transfer instructions, two words at a time.
 
SFC 20 doesnt seem to work..
I have a DB location say DB300 and 2.0 for the String structure format data to be moved STRING [16]

SOURCE BLK= P#db???.dbx?.? byte 16
DEST BLK= P#db300.dbx2.0 byte 16
i tried this but wont work.
 
Can you post the SFC20 code you tried and show what if any RET-VAL you had.

Also the source DB and destination DB.

SFC20 should work fine.
 
I can't see why that wouldn't work to be honest.

The RET-VAL your placing into a temp variable, if it fails it should place a code here.

The network was cut and paste off-line so cannot see which transfer is supposed to be taking place and what the RET-VAl is.
 
STRING [16] reflects 16 bytes right?
i always get confused with the data length
I can bytes and words and characters move to DB and make a STRING Data into CHAR but cant move STRING to STRING
 
I think It might work with moving
P#DB306.DBX2.0 Byte 18
P#DB305.DBX2.0 Byte 18

But I cant see if its working because the other which actually connects to mine to grab the Part Number is not running right now .

But still when i did try to go online with DB306 it wont go online but say a message that
The contents in the DB are not possible to be monitored online, first time I got a message like that...i checked the no red on the db it seems to save it ok and download to the PLC but cant view online.
 
You cannot monitor a string in a DB - view it as a series of characters in a VAT table to see what is going on.
 

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