Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

SWL, need an explanation, please.

Created by: yanyod at: 9/11/2012 6:39 PM (3 Replies)

Rating (0)

Thanks 0

4 Entries

9/11/2012 6:39 PM	Rate (0)
yanyod Posts: 10 Rating: (0)	Hi everyone. All is on the title. I'm doing an upgrade from a S5 115U CPU343B and I don't completely understand how SLW function works. In the source code : L DL 45 L KF +150 +F SLW 1 L KH E400 +F LIR 0 T DW 239 L KF +118 +F T DW 240 L DW 240 L DW 238 TNB 99 I've found on the user manual, SLW is to shift the content of ACCU 1 to the left by the n value. I also understand in this code it's to have the correct adress for the TNB function. But when I try to convert in binary code i have for 16#E400 -> 1110 0100 0000 0000. After the shift by 1 bit, I need to have in binary code 1100 1000 0000 0001 -> 16#C801, but with this result it's impossible to load an absolute adress for a data block. I'm so perplex soI think i absolutely don't understand the SLW function. Anyone can help me??? Yann
yanyod Posts: 10 Rating: (0)
Suggestion To thank Quote Answer

9/11/2012 11:46 PM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 11/6/2024 Posts: 3026 Rating: (1056)	Hello Yann_GPC SLW1 is simply a multiplication by 2. In your case it is applied to value that is created by adding DL45 value with a constant of 150 (SLW1is NOT appliedfor the16#E400DB startvalue, so I think you confused yourself a bit with that). Thereafter, the result is added to the absolute start address of DB0 (E400) toget the start address of the DB they are looking for. Thereason why the multiplication with 2 is done via SLW1, is that the DB start addresses in your943 CPU occupy 2 words each (e.g. DB0 start address is in E400 & E401, DB1 is in E402 & E403 and so forth). If DL45 for example has a value of 10, your logic calculatesthe absolute start address of DB160 and doesso quite correctly by first multiplying 160 with 2 before adding the resultto the absolute start address of DB0 (E400). I hope this helps
	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.
Suggestion To thank Quote Answer

9/12/2012 9:03 AM	Rate (0)
yanyod Posts: 10 Rating: (0)	Hellofritz, Thanks a lot for your support, it's very helpful. And with your explanation, it's clearer in my mind now. Best regards!
yanyod Posts: 10 Rating: (0)
Suggestion To thank Quote Answer

2/13/2014 1:37 PM	Rate (0)
GrasserF Posts: 340 Rating: (6)	new question is splittet i still dont understand slw
GrasserF Posts: 340 Rating: (6)
Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on