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Find empty DB

Created by: Saruca at: 11/4/2011 9:52 AM (5 Replies)

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11/4/2011 9:52 AM	Rate (0)
Saruca Posts: 122 Rating: (1)	Hi everyone, I'm writing a programme in which I need to find the first empty DB (from a list of previously created global DBs) and write some information on it. I had achieved that in STL but now I need to turn the code into SCL and I can't make it work. I tried using the same kind of expression (also similar to other high level programming languages) but it's not right. Could you give me a hand? This is the code I'm using. I'm no expert so if you know a better way to find the empty DB please share it. It would be very helpful. ************************************** STL code [code] L 10 T MW 40 buc: AUF DB [MW 40] L DBW 4 L 0 ==I SPB loc L MW 40 + 1 T MW 40 L 40 L MW 40 >I SPB err LOOP buc loc: NOP 0 err: NOP 0 [/code] SCL code [code] WHILE i <= NCajasmax DO IF DB[i].Destino:=0 THEN DB[i].PIC:=RegistroSalida.PIC; DB[i].Destino:=RegistroSalida.Destino; DB[i].Longitud:=RegistroSalida.Longitud; DB[i].Zapatos:=RegistroSalida.Zapatos; i:=i+1; //else numero de cajas demasiado elevado. error END_IF END_WHILE; [/code] Thanks in advance
Saruca Posts: 122 Rating: (1)
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11/7/2011 8:50 AM	Rate (0)
Aret Posts: 2348 Rating: (259)	Use WORD_TO_BLOCKDB conversion to make dynamic DB number
Aret Posts: 2348 Rating: (259)
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This contribution was helpful to 1 thankful Users Saruca

11/8/2011 11:31 AM	Rate (0)
Saruca Posts: 122 Rating: (1)	Thanks for your reply Aret. I will try that and post the outcome. I also thougth about doing that in another AWL function and calling it from my SCL function. I think the first choice, doing it in SCL directly, would be faster though. What do you think? Thanks again, Sara
Saruca Posts: 122 Rating: (1)
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11/8/2011 12:32 PM	Rate (0)
smiffy Platinum Expert Joined: 1/17/2007 Last visit: 5/31/2023 Posts: 1524 Rating: (522)	I have had a go at coming up with some SCL code. It might not meet your exact requirements, but it could be helpful. [code] FUNCTION_BLOCK FB100 VAR_TEMP i : INT; DB_LEN : WORD; WR_PROT : BOOL; RetVal : INT; END_VAR VAR_OUTPUT EmptyDBNum : INT; END_VAR FOR i := 1 TO 999 DO RetVal := TEST_DB(DB_NUMBER := INT_TO_WORD(i), DB_LENGTH := DB_LEN, WRITE_PROT := WR_PROT); IF (RetVal = 0) AND (WORD_TO_INT(DB_LEN) = 0) AND (WR_PROT = FALSE) THEN EmptyDBNum := i; EXIT; ELSE EmptyDBNum := -1; END_IF; END_FOR; IF EmptyDBNum >= 0 THEN ; // Your code ELSE ; // Your error handler END_IF; END_FUNCTION_BLOCK [/code]
	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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This contribution was helpful to 1 thankful Users Saruca

11/9/2011 11:28 AM	Rate (0)
Saruca Posts: 122 Rating: (1)	Hi smiffy, Thanks for your help. I've got a doubt about the program you suggest. I just want to check if the value of certain tag (or all the tags) in certain DB is zero. When I finish working with that DB I set to zero every tag inside it as a way of initializing it. Later, when I want to use it again I need to check that it is in fact empty. Can I do that using SFC24 TEST_DB as you suggest? This is what I have so far but it doesn't work. I can't get the condition in the IF structure to work. Could you have a look at it and tell me if you see something wrong? [code] WHILE i <= Nmax DO DBactivo:=INT_TO_WORD(i); IF WORD_TO_BLOCK_DB (DBactivo).DBW4=0 THEN WORD_TO_BLOCK_DB (DBactivo).DD0:=REAL_TO_DWORD(RegistroSalida.1); WORD_TO_BLOCK_DB (DBactivo).DW4:=INT_TO_WORD(RegistroSalida.2); WORD_TO_BLOCK_DB(DBactivo).DD6:=REAL_TO_DWORD(RegistroSalida.3); WORD_TO_BLOCK_DB (DBactivo).DW10:=INT_TO_WORD(RegistroSalida.4); i:=100; //ELSE numero de cajas demasiado elevado. error END_IF; i:=i + 1; END_WHILE;[/code] Thanks in advance
Saruca Posts: 122 Rating: (1)
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11/10/2011 11:35 AM	Rate (0)
Saruca Posts: 122 Rating: (1)	Nevermind. I made it work. The problem was some silly programming mistake outside the while loop. Thanks again
Saruca Posts: 122 Rating: (1)
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This contribution was helpful to 2 thankful Users smiffy O_Moderator

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