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Extract bit from word for a huge number of words

Created by: Palestine at: 10/6/2009 3:59 PM (22 Replies)

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10/6/2009 3:59 PM	Rate (0)
Palestine Posts: 74 Rating: (0)	Flomaster Hi! This is my first project using SIEMENS in STEP7 10.5 on LAD. I'm using S7-1200. I have variable of type WORD in my project. And I want to extract bits from this variable? But I don't know how can I do it. Can somebody explain it to me? Thanks! Hello Flowmaster i was going to ask the same question, so can any one help us please because i need it for a huge number of words best regards
Palestine Posts: 74 Rating: (0)	Last edited by: O_Moderator at: 10/9/2009 11:19 AM
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10/6/2009 6:06 PM	Rate (0)
Niranjan Prasad Posts: 691 Rating: (36)	you may access the bits of a word by getting the status of individual bits For Example L 16#209 T MW20 A m20.0 A M21.6 Attachment 01-05 word bytes bits.gif (2099 Downloads)
Niranjan Prasad Posts: 691 Rating: (36)
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10/7/2009 8:57 AM	Rate (0)
Palestine Posts: 74 Rating: (0)	Hello Chimpu thank you for the response, but the problem that i have to do this for maybe 200 words so what i need is another simple way easy to be checked again from another programmer, even if i have to build a new FC or FB to do that, with one input (word) and 16 output (bit). best regards
Palestine Posts: 74 Rating: (0)	Last edited by: Palestine at: 10/7/2009 8:58 AM
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10/7/2009 6:39 PM	Rate (0)
Niranjan Prasad Posts: 691 Rating: (36)	Whats your application i can't understand properly Do you want Indirect Addressing
Niranjan Prasad Posts: 691 Rating: (36)
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10/8/2009 11:21 AM	Rate (0)
Palestine Posts: 74 Rating: (0)	Hello thank you Chimpu, and i am sorry Flowmaster forinterruption. the project that i am reading from is an ASi Gateway, digital In/Out andanalogIn signals, for each Digital group i have 16 word each bit from these words connected with a separated tag or variable and i have 15 ASi GateWay so i will do it by ladder or if there is another way i will be grateful. best regards
Palestine Posts: 74 Rating: (0)
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10/9/2009 1:36 PM	Rate (3)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 6/9/2023 Posts: 2969 Rating: (1025)	Hello Palestine this Functionshould do what you are after, please note the following: Bit_0 that is "extracted" from theWORD is the LSB (least significant bit) and Bit 15 the MSB (most significant bit) and I treat the input Word to the FC as ONE WORD. What I mean by that is that if you use for example IW 20 as the FC's input word, Bit_0 reflectsI 21.0 and Bit_15reflects I 20.7. If you rather have it the other way round (i.e Bit_0 is I 20.0 and Bit_15 isI 21.7) simply rearange the TEMP bits. Anyway I hope this is what you are after and the source file (as shown below) is also attachedfor your convenience. [code]FUNCTION FC 7 : VOID TITLE =Extract Bits from Word VERSION : 0.1 VAR_INPUT WORD_IN : WORD ; END_VAR VAR_OUTPUT Bit_0 : BOOL ; Bit_1 : BOOL ; Bit_2 : BOOL ; Bit_3 : BOOL ; Bit_4 : BOOL ; Bit_5 : BOOL ; Bit_6 : BOOL ; Bit_7 : BOOL ; Bit_8 : BOOL ; Bit_9 : BOOL ; Bit_10 : BOOL ; Bit_11 : BOOL ; Bit_12 : BOOL ; Bit_13 : BOOL ; Bit_14 : BOOL ; Bit_15 : BOOL ; END_VAR VAR_TEMP Bits : STRUCT _8 : BOOL ; _9 : BOOL ; _10 : BOOL ; _11 : BOOL ; _12 : BOOL ; _13 : BOOL ; _14 : BOOL ; _15 : BOOL ; _0 : BOOL ; _1 : BOOL ; _2 : BOOL ; _3 : BOOL ; _4 : BOOL ; _5 : BOOL ; _6 : BOOL ; _7 : BOOL ; END_STRUCT ; END_VAR BEGIN NETWORK TITLE =Extract Bits from Word // Recommended way to keep symbolic addressing "happy" L #WORD_IN; // Load input Word LAR1 P##Bits; // Point AR1 to TEMP Bits T W [AR1,P#0.0]; // Store input Word in TEMP variable // Alternatively (NOTE: absolute access to TEMP variable) // L #WORD_IN// Load input Word // T LW 0// and store in Local Word 0 // Copy bits to outputs (could also be done in LAD/FBD if need be) A #Bits._0; = #Bit_0; A #Bits._1; = #Bit_1; A #Bits._2; = #Bit_2; A #Bits._3; = #Bit_3; A #Bits._4; = #Bit_4; A #Bits._5; = #Bit_5; A #Bits._6; = #Bit_6; A #Bits._7; = #Bit_7; A #Bits._8; = #Bit_8; A #Bits._9; = #Bit_9; A #Bits._10; = #Bit_10; A #Bits._11; = #Bit_11; A #Bits._12; = #Bit_12; A #Bits._13; = #Bit_13; A #Bits._14; = #Bit_14; A #Bits._15; = #Bit_15; NETWORK TITLE = Block End SET ; // RLO = 1 SAVE ; // ENO = 1 to allow cascading in LAD/FBD END_FUNCTION[/code] Attachment FC7.zip (951 Downloads)
	Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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10/10/2009 10:35 AM	Rate (0)
Palestine Posts: 74 Rating: (0)	fritz thank you, it is exactly what i need, but when i use // L #WORD_IN // Load input Word LAR1 P##Bits // Point AR1 to TEMP Bits T W [AR1,P#0.0] // Store input Word in TEMP variable it it dose not work and i have an internal error can youcheckthe attached pictures. unless i use the other option: // Alternatively (NOTE: absolute access to TEMP variable) L #WORD_IN // Load input Word T LW 0 // and store in Local Word 0 best regards Attachment Extract bit from word.JPG (1735 Downloads)
Palestine Posts: 74 Rating: (0)	Last edited by: Palestine at: 10/10/2009 2:08 PM
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10/10/2009 2:03 PM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 6/9/2023 Posts: 2969 Rating: (1025)	Hello again Palestine not too sure why it won't work in your case. I did admittedly quickly "hack" FC7 together, but did test it before posting it (and just testedit again and it works fine). Your error relates to FC99(I presume though that this is the block I posted, correct?) and more importantly to a write problem with the TEMP variablesof FC99. I wonder if you used the source file that I posted OR copied the code "printout" in my post and - if so - possibly forgot to create the 16 TEMP bits (which would explain the error that you are getting). Anyway, to besure to be sure, please find attached FC7 as a "ready to go" block inside a Step7library, give it a try and please let me knowthe outcome. Last but not least, the logic in your screendump really does nothing else than copyingPIB516 onto MB3 and PIB517 onto MB2 (I thought you want toextract bits froma Word an copy them onto "scattered" memory (or DB) bit addresses). Perhaps your screendump only shows a test logic, butjust in case this is all you want to achieve, you will be far better off with this logic: [code]L PIW 516 CAW // swap high and low byte T MW 2[/code] All that's left to do is todeclare symbol names for MW 2 as well as M 2.0 -> M3.7 and then use the individual bits as needed. I hope this helps Attachment Fc7.zip (607 Downloads)
	Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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10/10/2009 2:19 PM	Rate (0)
Palestine Posts: 74 Rating: (0)	fritz thank you,it is exactly what i need, but when i use // L #WORD_IN // Load input Word LAR1 P##Bits // Point AR1 to TEMP Bits T W [AR1,P#0.0] // Store input Word in TEMP variable it it dose not work and i have an internal error. unless i use the other option it works perfect: // Alternatively (NOTE: absolute access to TEMP variable) L #WORD_IN // Load input Word T LW 0 // and store in Local Word 0 but what is the last line? is it MW0 or another memory location? best regards
Palestine Posts: 74 Rating: (0)
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10/11/2009 12:08 PM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 6/9/2023 Posts: 2969 Rating: (1025)	Palestine but what is the last line? is it MW0 or another memory location? Hey Palestine "L" nominates"Local" memory which is bettwr known as the TEMP variable area of the block. "LW 0" is the first WORD of the TEMP area. You'd "normally" useTEMP's symbolically in your Block (and if done, you'll note thatthey still have a symbolic name even if you untick "Symbol" view). TEMP's do however have an "address" which can also be used (and is used in thiscase as the first 16 TEMP bits are declared as individual bits insteadof typeWORD). The downside of doing this is that if you were to add (or remove) TEMP variables which would lead to a shift of the "directly addressed" one you will have to remember that direct addressing is done and make the required changes in your logic. Anyway, none of the above expains why the AR1 based logic doesn't work (which has to work), have you had a change to test the FC7 from the library yet?
	Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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