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What is the difference between L and L L# ?

Created by: Jackie114 at: 4/7/2014 2:16 AM (2 Replies)

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4/7/2014 2:16 AM	Rate (0)
Jackie114 Posts: 71 Rating: (0)	Hi, all, I am confused with L and L L#, such as: 1, L 80 T MD20 …… L 80 T MW20 …… 2, L L#80 T MD20 …… L L#80 T MW20 …… Could you tell me what are values in MD20 and MW20 in case 1 and 2? Because I read a paper about pointer, but sometimes it said MD20 (or MW20) = 80 and sometimes it said MD20 (or MW20) = 10.0. I know how to get 10.0（80H = 0000 0000 0000 0000 0000 0000 0101 0000B）. But I cannot understand why it is 80 not 10.0 or it is 10.0 not 80. Thanks a lot.
Jackie114 Posts: 71 Rating: (0)
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4/7/2014 5:39 AM	Rate (0)
Ste39 Platinum Member Joined: 1/21/2013 Last visit: 10/23/2024 Posts: 4620 Rating: (708)	Hello Jackie114, in other words L 80 is a 16 bitsconstant(2-BYTE 1-INTEGER) and L L#80 is a 32 bit constant(4 BYTE-2 INTEGER-1 DOUBLE INTEGER). In STEP 7 press F1 for help. L 10.0 is a 32 bit REAL number with POINT and SIGN. Have a look: Step 7 Elementary Data Types \| PLCdev
	Last edited by: Ste39 at: 4/7/2014 6:17 AM Last edited by: Ste39 at: 4/7/2014 5:45 AM
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4/7/2014 3:31 PM	Rate (2)
Aret Posts: 2348 Rating: (264)	Difference between INT and DINT can be clearly seen here L L#100000 // exceeds INT, so only DINT possible L -1 +D // here you will get not 99999. To make this calculation correct you must use L L#-1 instead. Try both codes with monitoring and you will remember the difference
Aret Posts: 2348 Rating: (264)
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