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queue command

Created by: HOWERLIN at: 11/15/2011 2:56 PM (6 Replies)

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11/15/2011 2:56 PM	Rate (0)
HOWERLIN Posts: 25 Rating: (0)	Does S7-1200 have queue command? That is, if I want to use an array to store data as store in a queue( or list), which have commands like Insert At Top, Insert At Bottom, Insert at Middle, Remove Top, Remove Bottom...... Thanks
HOWERLIN Posts: 25 Rating: (0)
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11/15/2011 5:04 PM	Rate (0)
William_B Posts: 5225 Rating: (1195)	HOWERLIN Does S7-1200 have queue command? That is, if I want to use an array to store data as store in a queue( or list), which have commands like Insert At Top, Insert At Bottom, Insert at Middle, Remove Top, Remove Bottom...... Hi there, The set of commands you are looking for is what I know as TABLE COMMANDS from the S7-200 PLC. I do not know of a direct set of commands or a library available. A search is given this LINK as result. It makes use of FieldRead & FieldWrite. [UPDATE 1: this function was used in Step 7 V10.5, not required for V11.0] [UPDATE 1: V11.0 accepts pointer value inside array as used below.] It should be possible to design your own table commands. Something like.. (forgive the rough outline notation) A1 is array [0..9] of INT // primary array A2 is array [0..9] of INT // temporary storage value is INT // value to fit in table size is INT // size of table (1) INSERT TOP MOVE_BLK( A1[0], 9, A2[1] ) MOVE( value, A2[0] ) MOVE_BLK( A2[0], 10, A1[0] ) ADD( size, 1, size) (2) REMOVE BOTTOM MOVE( 0, A1[size] ) SUB( size, 1, size ) and so on..
William_B Posts: 5225 Rating: (1195)	Last edited by: William B. at: 11/15/2011 5:16 PM UPDATE 1 Last edited by: William B. at: 11/15/2011 5:05 PM
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11/15/2011 5:52 PM	Rate (0)
William_B Posts: 5225 Rating: (1195)	UPDATE: According to a document "SIMATIC S7-200 to SIMATIC S7-1200 software conversion tool" dated January 2010 there are no equivalent commands in the S7-1200 for the following S7-200 (table) commands: LIFO Last In First Out FIFO First In First Out ATT Add to Table TBL_FIND Table Find Anyone else.. is that still true? Has someone developed a library for such commands yet? I think this is +/- what HOWERLIN requires.
William_B Posts: 5225 Rating: (1195)
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11/15/2011 6:06 PM	Rate (0)
Ganes10 Platinum Member Joined: 8/31/2010 Last visit: 11/6/2024 Posts: 1523 Rating: (229)	HOWERLIN Does S7-1200 have queue command? That is, if I want to use an array to store data as store in a queue( or list), which have commands like Insert At Top, Insert At Bottom, Insert at Middle, Remove Top, Remove Bottom...... Thanks Hello HOWERLIN, There are two instruction known as FieldRead and FieldWrite. These will do your work so easily. Get the details on FieldRead and FieldWrite instructions from here
	Last edited by: Ganes10 at: 11/15/2011 6:07 PM Like it? Rate it!
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11/16/2011 8:38 AM	Rate (0)
William_B Posts: 5225 Rating: (1195)	Ganes10 There are two instruction known as FieldRead and FieldWrite. These will do your work so easily. Sorry Ganes10, I have to +/- disagree with you on this. These commands are not TABLE commands. FieldRead and FieldWrite can be used to develop your own code, but these commands are not required inside Step 7 V11.0. You can develop code without FieldRead and FieldWrite. In V11.0 we can now say ArrayName [ INT_Variable ]... MyArray[N]. This was not possible in V10.5. For V10.5 was only possible ArrayName [ Constant ]... MyArray[2]. So you had to use other methods to extract data from an array set, namely FieldRead and FieldWrite. FieldRead and FieldWrite does not offer an automatic solution to the original question. There is still code to develop or import from a library. Then for Step 7 V11.0 you can decide to use the FieldRead and FieldWrite commands or not use them. Was I now clear as mud?
William_B Posts: 5225 Rating: (1195)	Last edited by: William B. at: 11/16/2011 8:59 AM
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11/16/2011 12:20 PM	Rate (0)
HOWERLIN Posts: 25 Rating: (0)	Thanks all, so maybe we need to use FieldRead and FieldWrite and some function to maintain the structure of data array. Originally, I guess there will be some convinient command for process array data. For example : An array stores 1, 2, 3, 4, 5 After InsertAtTop(array,0), the array become 0,1,2,3,4,5 After RemoveBottom(array), the array become 0,1,2,3,4 So that we don't need to care about the size of this array, in some other PLC, it has function like this.
HOWERLIN Posts: 25 Rating: (0)
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11/16/2011 3:25 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 11/8/2024 Posts: 15388 Rating: (2443)	HOWERLIN Thanks all, so maybe we need to use FieldRead and FieldWrite and some function to maintain the structure of data array. Originally, I guess there will be some convinient command for process array data. For example : An array stores 1, 2, 3, 4, 5 After InsertAtTop(array,0), the array become 0,1,2,3,4,5 After RemoveBottom(array), the array become 0,1,2,3,4 So that we don't need to care about the size of this array, in some other PLC, it has function like this. Unfortunately, you cannot change the array lo/hi definitions at runtime. Once established, you need to manage the contents and pointers to the contents yourself (manually). For example, if you create a DB structure similar to this: QueueDB: MyQueueArray : Array[0..100] of INT TopIndex : INT BotIndex : INT etc. Then create FBs to manage the QueueDB: FB_EnQueue - input queueData : INT - use a temporary Array of the same size as MyQueueArray to add to the queue and adjust the top/bottom as required FB_DeQueue - output queueData : INT - use a temporary Array of the same size as MyQueueArray to remove an item from the Queue and adjust the top/bottom as required. FB_InitQueue - Set QueueDB.TopIndex = 0 - Set QueueDB.BotIndex = 0 - Set QueueDB.MyQueueArray[0..100] = 0 --- Once you get something working, please feel free to share your 'queue library' :)
	science guy
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This contribution was helpful to 1 thankful Users William_B

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