S5 to S7 anyone translate this bit for me?

[Johnny T]

Hi

I'm converting some old S5 code into S7. I've got the following code in S5:

C DB 100
DO FW 223
L DW 0
T FW 220

I want to convert this to S7. I understand that its moving a word equivalent to the value of FW 223 into FW 220 but don't know how to do this in S7. I ideally want to do it in ladder if possible.

So, basically I want something along the lines of a MOVE function that 'moves' DB100.DBW[MW223] into MW220.

Obviously this doesn't work so I wondered if anyone knows the correct and most efficient way to replicate this in S7.

Many thanks

JT ;-)

 

[10BaseT.]

Why doesn't it work ?

 

[Johnny T]

I don't know. But if I put a MOVE function in LADDER and enter DB100.DBW[MW223] then I get a syntax error and it comes up in red?

Any ideas?

 

[L D[AR2P#0.0]]

You have to open the DB first and then do the transfer with L DBW[MW223]. You can't do this in ladder.

 

[Johnny T]

It doesn't work. I think its because its wanting a Doubleword so that it can access it as a pointer.

So... L DBW[MD 223] works but L DBW[MW 223] doesn't...

The problem is that in the software if Flag Bytes 225 and 226 are used then this is going to end up with unexpected results.

Any ideas how I can use DBW[MW223] or any code that would give me the equivalent?

Cheers

JT ;-)

 

[Johnny T]

Your username has just given me an idea....

Would this work:

L MW 223
L D [AR1,P#0.0]
T MW 220

????

 

[L D[AR2P#0.0]]

Create a temp variable of type dword, say dwAddress
then:

L MW223
SLD 4  //convert address to s7 pointer format
T dwAddress
L DBW[dwAddress]

 

[Johnny T]

Nice one!

That's what I'll do.

Thanks for the solution.

Cheers

JT ;-)

 

[Johnny T]

Right, I've just had a go at this and think I've come up with the best solution. I've created an FC that is the equivalent to the S5 'do' function. You give it the DB number, the 'DO' word and the destination and it does the rest itself. This code isn't tested but I've posted it below just in case anyone is interested.

NB. I say again.. THIS CODE ISN'T TESTED USE AT OWN RISK

  

FUNCTION "'DO' FUNCTION EQUIVALENT" : VOID

TITLE =

VERSION : 0.1



VAR_INPUT

  WHAT_DB : BLOCK_DB ; 

  WHAT_WORD : WORD ; 

  WHAT_DESTINATION : WORD ; 

END_VAR

VAR_TEMP

  DOUBLE_VALUE : WORD ; 

  TEMP_POINTER : DWORD ; 

END_VAR

BEGIN

NETWORK

TITLE =PURGE VALUES

 

      A(    ; 

      L     0; 

      T     #DOUBLE_VALUE; 

      SET   ; 

      SAVE  ; 

      CLR   ; 

      A     BR; 

      )     ; 

      JNB   _008; 

      L     L#0; 

      T     #TEMP_POINTER; 

_008: NOP   0; 

NETWORK

TITLE =OPEN REQUIRED DATABLOCK

      OPN   #WHAT_DB; 

NETWORK

TITLE =MULTIPLY WORD BY TWO TO CONVERT FROM S5 TO S7 ADDRESSING

      L     #WHAT_WORD; 

      L     2; 

      *I    ; 

      T     #DOUBLE_VALUE; 

      NOP   0; 

NETWORK

TITLE =CHANGE WORD INTO A POINTER BY SHIFTING BITS LEFT

      L     #DOUBLE_VALUE; 

      SLD   4; 

      T     #TEMP_POINTER; 



NETWORK

TITLE =TRANSFER INDIRECTLY ADDRESSED VALUE INTO REQUIRED DESTINATION

      L     DBW [#TEMP_POINTER]; 

      T     #WHAT_DESTINATION; 

 

PS. The reason I double the word that is originally given is because in S5 the words are addressed 0,1,2.. etc but in S7 they are addressed 0,2,4.. etc

;-)

 

[L D[AR2P#0.0]]

Notes on your FC:

Purge is not required as the variables are always loaded later on so you can delete network 1.
The SLD 4 is already multiplying by two so you can delete network 2.
Load WHAT_WORD instead of DOUBLE_VALUE in network 3.

(Another warning - I believe the DO instruction performs an 'or' with the operand of the following instruction. I haven't seen it used, but you may come across the following in which case the contents of FW223 are ored with 1 to form the address !

C DB 100
DO FW 223
L DW 1)

 

[Johnny T]

Right, I've changed that now. Thanks for pointing all that out.

You could be right about the 'ORing' with the DO command. In the software that I'm translating, so far I've only seen L DW0 commands and not a L DW1.

If I find a '1' or other number somewhere I'll alter my function to include an 'ORing' number as well.

Many thanks for your help on this. Hope you have a great Christmas mate.

Cheers

JT ;-)

 

[parky]

Call DB100

DO fw223 (process the value in fw223 say 200)
LDW0 (load dw 200 in other words load the dw of the value
in fw223)
t FW226 Store it
example
l kf1 pointer to DW
t fw200 pointer stored in temp fw
c db 100 call db
do fw200
l dw0 (loads dw1)