SCL Indirect DB

[cjd1965]

Hi I am trying to read data from various DB's

So "DB_HMI".Data1 := DB[PARAM].Data1

etc

where PARAM = 1 to 99

 

[JesperMP]

I think you cannot do it symbolically like you have it in your own example.
To access a DB indirectly you loose the symbolic connection.

Something like this should work for a WORD-sized address (INT, or WORD):
"DB_HMI".Data1 := WORD_TO_BLOCK_DB(PARAM_DBNR).DW[PARAM_WORDNR] ;

Something like this should work for a DWORD-sized address (DINT, DWORD or REAL):
"DB_HMI".Data1 := WORD_TO_BLOCK_DB(PARAM_DBNR).DD[PARAM_DWORDNR] ;

edit: In my example also the element is indirectly specified. This may not be necessary for your application.
In that case you can write for example:
"DB_HMI".Data1 := WORD_TO_BLOCK_DB(PARAM_DBNR).DW10 ;

edit again: Maybe PARAM_DBNR is an INT because you want to loop through 1..99.
In that case you can do:
"DB_HMI".Data1 := WORD_TO_BLOCK_DB(INT_TO_WORD(PARAM_DBNR)).DW10 ;

 

[cjd1965]

Hi thanks

I think I will cheat and just write 99 fc's with awl cut & paste

Pity it was not made easier

Cheers

 

[JesperMP]

Because of the symbols ?

 

[L D[AR2P#0.0]]

So "DB_HMI".Data1 := DB[PARAM].Data1

etc

where PARAM = 1 to 99

As there is no variable part on the left hand side of the assignment can you expand on the "etc" part

 

[inalvor1]

If .data1 is a struct, can you not use DB_HMI".Data1 as destination pointer for SFC20?

Then just create a temp struct for an anypointer, which you feed manually with values. Then you have symbolic dbno.

Measure .data1 length for repetition factor.

 

[cjd1965]

Hi All

Basically we supplied a machine with a fixed set of parameters for 99 different possible vessels (it is a washer, and yes, we told the customer it was a bad idea)

Now, it has been identified that we need a crude recipe system. I already have a global DB which is the existing setpoints. However the DB also has lots of other items scattered in it such as timer elapsed values, status messages etc.

I was asked TODAY to write some code to fix it for testing onsite TOMORROW..... typical bs etc.

Anyway I exported the global DB and stripped out the parameters (approx. 80) , then copied this to 99 DB's, 1 for each vessel. I know I could have used a UDT but time was limited

The data is a mix of INTs and REALs.

I have written a set of 5 FC's which are basically IF Product1 THEN load parameters for Product1 to the original working DB through to 99 and used a offset in the HMI tag to point to the new Product DB for the data read/write

If I was doing this from the ground up I would probably have used SFC20 and kept the parameters separate.

Would have been so simple if I could have kept the DB[number] style

Will check back here later when at home
Cheers

 

[cjd1965]

Hi Having been tagging up the HMI indirect addresses I think this task would have been easiest as a HMI script due to not having symbolic programming available due to indirect requirment.

Having said that I prefer to keep as much as possible of any logic etc in the PLC.

 

[cjd1965]

Hi Jesper
I have more time on this so I am going to investigate post#2 in more depth.

Cheers