siemens s7 symbolic field list

[L D[AR2P#0.0]]

Yes, a DB pointer is stored in memory as follows:

DB number - word
AreaPointer - dword

 

[uptown47]

Example implementation:

In the interests of furthering my learning I've been looking through LD's example code.

2 questions spring to mind...

1) Am I right in thinking that the TAK command is there to take put the 'new' value (after detecting the words are different) into ACCU1 so that it can be transferred to the 'copy' table? If so, I presume that if order in which the DB's were opened and compared was the other way around then the TAK wouldn't be needed?

i.e.

If we used:
OPN DB[#iCopyDB]
L W[AR1,P#0.0]
OPN DB[#iTableDB]
L W[AR2,P#0.0]
==I
JC past
S #bChangeDetected
TAK // Now we don't need this, right??
T W[AR1,{#0.0]
etc etc

2) Am I right in thinking that M100.0 (the RET VAL) will one be on for 1 scan as, the next scan, the DB's will be equal again so it will go off ??

Is this correct??

Thanks

;-)

 

[L D[AR2P#0.0]]

1) Which DB is open when the T W[AR1,P#0.0] is executed ?

2) Quite right.

 

[uptown47]

1) Which DB is open when the T W[AR1,P#0.0] is executed ?

Ahhhh... ofcourse..... silly me!!!

Thank you.