steen.bill
Member
Hello.
How can i change this offset value P#0.0 to a variabel.. fx. a DBW
How can i change this offset value P#0.0 to a variabel.. fx. a DBW
S7: Pointer offset as variabel
- Thread starter steen.bill
- Start date
Peter Nachtwey
Member
You can't
You need to change AR1 itself by adding the offset to LAR1.
You need to change AR1 itself by adding the offset to LAR1.
Bratt
Lifetime Supporting Member
It can be done like this
Code:
L P#6.0 // Load ACCU 1 with pointer value.
T MD 2 // Transfer pointer into MD2.
OPN DB 1 // Open datablock 1
L 10
T DBW [MD 2] // Transfer value 10 to db1.dbw6
L P#2.0 // Increase pointervalue in md2 with 2 bytes
L MD 2
+D
T MD 2
L 25
T DBW [MD 2] // Transfer value 25 to db1.dbw8PeterW
Member
See the line 3 below the one you circled.
+AR1 P#2.0
This is changing the offset by 2 bytes, or the next word.
3 lines before the circled code, is where AR1 is originally set
LAR1 P#DBX0.0
If you want to vary the start point, you could use the +AR1 instruction after the LAR1 instruction and use a variable to do the offset.
i.e. prior to the code you can see have something like
L 2 <== could be variable
SLD 3
T MD500
Then after the LAR1 put
L MD500
+AR1
+AR1 P#2.0
This is changing the offset by 2 bytes, or the next word.
3 lines before the circled code, is where AR1 is originally set
LAR1 P#DBX0.0
If you want to vary the start point, you could use the +AR1 instruction after the LAR1 instruction and use a variable to do the offset.
i.e. prior to the code you can see have something like
L 2 <== could be variable
SLD 3
T MD500
Then after the LAR1 put
L MD500
+AR1
L D[AR2P#0.0]
Lifetime Supporting Member
The variable name suggests you are looping through a number of reals yet you are loading/transferring words - might be a bit confusing in the future.
steen.bill
Member
OP
Hi again.
It's a cut from other program... and of coarse it will be changed to "No_of_Words"
I try to make the same function as TI505 - MWI Move With Index
It's a cut from other program... and of coarse it will be changed to "No_of_Words"
I try to make the same function as TI505 - MWI Move With Index
Peter Nachtwey
Member
Can't you simply use BLKMOV, FC20? Otherwise I would write a FC that has a source and destination pointer and a count.
L D[AR2P#0.0]
Lifetime Supporting Member
Do you require two indexes, one for the source and one for the destination ?
What format do the indexes take, ints specifying the byte offset or pointers so you can specify DBW60 (for example) as the parameter ?
What format do the indexes take, ints specifying the byte offset or pointers so you can specify DBW60 (for example) as the parameter ?
Last edited:
steen.bill
Member
OP
Do you require two indexes, one for the source and one for the destination ? Yes, just what i want
fx. 60 for "read from DB60" and 61 for "write to DB61"
What format do the indexes take, ints specifying the byte offset or: Yes, like offset from DB62.dbw0 Same offset for both indexes..
pointers so you can specify DBW60 (for example) as the parameter ?
What format do the indexes take, ints specifying the byte offset or: Yes, like offset from DB62.dbw0 Same offset for both indexes..
pointers so you can specify DBW60 (for example) as the parameter ?
Peter Nachtwey
Member
Wow, Siemens must be proud of the URLs, they are sooooo long
http://www.google.com/url?sa=t&sour...Ve0ZBJ9wYLtAcLcRg&sig2=dNNhnQHStTxI_LXW6iqcjw
On page 6-104 the MWI instruction clearly shows that there is a source pointer, destination pointer and a count.
On page 6-90 there is the MOVE instructions that has a pointer and index for both the source and destination as well as a count.
If Bill is trying to emulate the MOVE instruction then one more parameter would be needed to scale the index into bit, byte, words and dwords offsets.
http://www.google.com/url?sa=t&sour...Ve0ZBJ9wYLtAcLcRg&sig2=dNNhnQHStTxI_LXW6iqcjw
On page 6-104 the MWI instruction clearly shows that there is a source pointer, destination pointer and a count.
On page 6-90 there is the MOVE instructions that has a pointer and index for both the source and destination as well as a count.
If Bill is trying to emulate the MOVE instruction then one more parameter would be needed to scale the index into bit, byte, words and dwords offsets.
steen.bill
Member
OP
Just like this, but of coarse, in S7 i also have to define DB..
steen.bill
Member
OP
More MWI..
L D[AR2P#0.0]
Lifetime Supporting Member
Code:
FUNCTION FC 1 : VOID
TITLE =
VERSION : 0.1
VAR_INPUT
i_DB_Read_from : INT ;
i_Offset_read : INT ;
i_DB_Write_to : INT ;
i_Offset_write : INT ;
iNoofWords : INT ;
END_VAR
VAR_TEMP
iLoopCount : INT ;
iDB : INT ;
END_VAR
BEGIN
NETWORK
TITLE =
L #i_DB_Read_from;
T #iDB;
OPN DB [#iDB];
L #i_DB_Write_to;
T #iDB;
OPN DI [#iDB];
LAR1 P#DBX 0.0;
L #i_Offset_read;
SLD 4;
+AR1 ;
LAR2 P#DIX 0.0;
L #i_Offset_write;
SLD 4;
+AR2 ;
L #iNoofWords;
LA: T #iLoopCount;
L W [AR1,P#0.0];
T W [AR2,P#0.0];
+AR1 P#2.0;
+AR2 P#2.0;
L #iLoopCount;
LOOP LA;
SET ;
SAVE ;
END_FUNCTIONPeter Nachtwey
Member
L D [AR2,P#0.0], did you use LAR2 P#DIX 0.0 just to set the upper area bits? Isn't there way around having to do this by forcing the L D [AR2,#P0.0] instruction to use the DI register by saying L DIW [AR2,#P0.0]? Or must the area bits always be set?
steen.bill
Member
OP
Thanks.
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