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How convert or read UDint to bool ?!

Created by: Bill1777 at: 12/19/2013 10:01 AM (6 Replies)

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12/19/2013 10:01 AM	Rate (0)
Bill1777 Bronze Member Joined: 4/30/2011 Last visit: 1/9/2022 Posts: 223 Rating: (4)	How convert or read UDint to bool ?! I need read 1-st bit from UDint and triger bool tag

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12/19/2013 2:32 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 1/24/2025 Posts: 15558 Rating: (2468)	AndyNeva How convert or read UDint to bool ?! I need read 1-st bit from UDint and triger bool tag In s7-1200/1500, you can slice with the .x1 after the tag name. Example, let us say MyDint is DINT = 0x0F0F MyDint.x1 will give you 1 MyDint.x8..MyDint.x15 = 0 Since you did not state what PLC family, this may be all the answer you need.
	science guy
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12/19/2013 8:17 PM	Rate (2)
Ganes10 Platinum Member Joined: 8/31/2010 Last visit: 1/24/2025 Posts: 1523 Rating: (230)	AndyNeva How convert or read UDint to bool ?! I need read 1-st bit from UDint and triger bool tag Hello AndyNeva, Have a look at this FAQ - How in STEP 7 (TIA Portal) can you access the unstructured data types bit-by-bit, byte-by-byte or word-by-word and symbolically? Hope this helps.
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This contribution was helpful to 2 thankful Users 0_Einstein Adrian Negre

12/20/2013 10:08 AM	Rate (0)
Bill1777 Bronze Member Joined: 4/30/2011 Last visit: 1/9/2022 Posts: 223 Rating: (4)	Tks a lot its work BUT: I have Status Tag (Udint) in Alarm Group which link to PLC. Status Tag trigered ONLY in HMI , but when I linked Status Tag to plc its dont correctly reading ?! (in HMI - on, in PLC - off) Attachment tag.zip (404 Downloads)
	Last edited by: AndyNeva at: 12/20/2013 10:54 AM
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12/20/2013 6:40 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 1/24/2025 Posts: 15558 Rating: (2468)	AndyNeva Tks a lot its work BUT: I have Status Tag (Udint) in Alarm Group which link to PLC. Status Tag trigered ONLY in HMI , but when I linked Status Tag to plc its dont correctly reading ?! (in HMI - on, in PLC - off) I have run across similar problems as I grow accustomed to "the Siemens way" of handling bytes/words/double words. These are device dependent and need to be understood before tackling the bits and bytes within words/dwords. For HMI/PLC applications using s7-1200/1500, for my more recent applications, I handle them like this: PLC DWORD @ DW200 Look in the watch table for DBB200, 201, 202, 203 (or where your plc dword is). Look where the HMI bit comes in. It will likely be either .x8 or .x16 (.x8 has been more common for me). a DWORD of memory in S7-1200/1500 is different than s7-300/400 as far as the layout goes. Once you understand the byte order differences, it may change how you setup alarm fields. To make it really simple, have an array of 4 bytes, and then you pick the right array element, right bit, and it works the same on both ends without thinking about it. Should also work on s7-300/400 and s7-1200/1500 implementations without changes.
	science guy
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12/20/2013 10:12 PM	Rate (0)
Bill1777 Bronze Member Joined: 4/30/2011 Last visit: 1/9/2022 Posts: 223 Rating: (4)	Tks Dword bit 8 sometimes work, sometimes DONT work (( Maybe exist another way to reed Alarm Status Tag in PLC ?!
	Last edited by: AndyNeva at: 12/22/2013 10:47 AM Last edited by: AndyNeva at: 12/22/2013 10:44 AM Last edited by: AndyNeva at: 12/20/2013 10:25 PM
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12/22/2013 10:13 AM	Rate (0)
Ganes10 Platinum Member Joined: 8/31/2010 Last visit: 1/24/2025 Posts: 1523 Rating: (230)	AndyNeva Tks a lot its work BUT: I have Status Tag (Udint) in Alarm Group which link to PLC. Status Tag trigered ONLY in HMI , but when I linked Status Tag to plc its dont correctly reading ?! (in HMI - on, in PLC - off) Hello AndyNeva, This is the typical bit positions for symbolic tags in S7-1200.
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