SiePortal

The integrated platform for your product selection, buying and support workflow - bringing together Industry Mall and Online Support.

Products & Services
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
Support Support
{{(apiData.Support | filter:{'rank':1}:true)[0].title}} Support
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
MySiePortal MySiePortal
{{(apiData.MySiePortal | filter:{'rank':1}:true)[0].title}} MySiePortal
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
Cart ({{apiData.CartCount}})

Navigation

Swaped word

5/5/2008 5:21 PM	Rate (1)
jul's Posts: 58 Rating: (1)	Hi everybody !! I've got a question about the memory management. Well, I see that in wincc V6.2 SP2 when configure my alarms in the alarm logging, the bit of the words are swaped. I explain: I have an alarm word DB10.DBW0 with 16 alarms. When i configure them, to have the firts alarm i have tu put the Bit 8, the second Bit 9... so i have : DB10.DBX0.0 = BIT 8 DB10.DBX0.1 = BIT 9 DB10.DBX0.2 = BIT 10 DB10.DBX0.3 = BIT 11 DB10.DBX0.4 = BIT12 DB10.DBX0.5 = BIT13 DB10.DBX0.6 = BIT14 DB10.DBX0.7 = BIT15 DB10.DBX1.0 = BIT0 DB10.DBX1.1 = BIT1 DB10.DBX1.2 = BIT2 DB10.DBX1.3 = BIT3 DB10.DBX1.4 = BIT4 DB10.DBX1.5 = BIT5 DB10.DBX1.6 = BIT6 DB10.DBX1.7 = BIT7 Why ? i have the same things with double word... Thanks Julien
jul's Posts: 58 Rating: (1)
Suggestion To thank Quote Answer

5/5/2008 5:40 PM	Rate (0)
Manchat Posts: 33 Rating: (6)	This is down to the way S7 PLCs handle Bits, Bytes, and Words. The 16 bit Word 0 is made up up of Byte 0 and Byte 1. Bit 0 of the 16 bit word is then Bit 1.0 and not 0.0 as most people would expect an bit 8 is Bit 1.0. Once you figure this out the programming becomes straightforward.
Manchat Posts: 33 Rating: (6)
Suggestion To thank Quote Answer

5/6/2008 8:55 AM	Rate (1)
jacek d Platinum Expert Joined: 9/23/2005 Last visit: 1/16/2026 Posts: 5155 Rating: (772)	This issue is caused by method of data storage in a memory in PCs and S7 CPUs. PCs (x86) use so-called low-endian method or byte order. S7 CPUs (MOTOROLA) use big-endian. More on this topic you can learn here.
	Regards, Jacek What is confusing you is the fact that you never see a number but always its digit representation. So you end up thinking that the number is the representation. - Andrej Bauer Any claims against me - based on whatever legal reason - resulting from the use of any code and/or ideas presented on this forum shall be excluded. #StayWithUkraine
Suggestion To thank Quote Answer

Share this page:

Share this page on...