Good evening,

Have been working on a small code which has to be developed in SCL. The primary functionality of this SCL program is to read and write from a instance DB. For ex, I have a PID and a instance DB associated with the PID. In the SCL program I got to read couple of DB values of this PID and then after internal computation in the SCL got to write back into the same instance DB of the PID. Went thru some topics and little confused on how to go with this.

Feedbacks or sample codes are highly appreciated.

Thank you and good day

Nil

Nil96

Good evening,

Have been working on a small code which has to be developed in SCL. The primary functionality of this SCL program is to read and write from a instance DB. For ex, I have a PID and a instance DB associated with the PID. In the SCL program I got to read couple of DB values of this PID and then after internal computation in the SCL got to write back into the same instance DB of the PID. Went thru some topics and little confused on how to go with this.

Feedbacks or sample codes are highly appreciated.

Thank you and good day

Nil

The easiest way is to declare some IN and/or IN/OUT parameters of the same data type as the few DB values you need to read or read_and_write. You can then decide if the SCL code is in an FC or FB code block.

IN/OUT would be my choice within an FC. The values are passed on to the FC and the FC passes the changes back to the original value.

Alternatives exists that make use of indirect addressing.. but it is doubtful if you require this for your program.

w

Hi,

Thanx for the post. I am gona create FB by the by. Anyway having some IO pins, dont want to interlink the DB and FB via interconnections. I just want to pass values from and to DB vis some pointers or any other addressing meathods. If there are some SFC or SFB  available wud like to make use of the same.

Regards

Hi,

For pointer addressing see this link as a start:

How can you construct an ANY pointer in S7-SCL using the AT function?

You also may need this information:

ANY, POINTER in SCL

I hope I could help!

Hi,

all variables in TIA Portal have "global" scope... it's just a matter of addressing them. You can easily access any variable of any db (glob or instance) from any FB or FC there is...

Be careful about using ANY ptr. I for example, did not manage to make it point to single to single bit... Because of that, I'd suggest you to use "Indirect Addressing": link. It is very useful particularly for implementing loops (indexing etc...) 

Janko

jankoslayer

all variables in TIA Portal have "global" scope... 

Janko -  [most] not [all].

Variables declared as "TEMP" is not meant to be read outside the blocked it was formed in. In the older PLC families it is sort-of possible.

Also (when mentioning later TIA-PLC combinations) the variables declared as "CONST" variables inside a code block, are also not available everywhere. But "CONST" is not an actual parameter but rather compile/software feature (as far as I know). 

As a forum note: SCL published under the "Step7 Additional Software" heading is meant as the SCL add-on package for Step7 V5.x.

^{No malice meant with the above text.}
Regards,
w

William

Janko -  [most] not [all].

Variables declared as "TEMP" is not meant to be read outside the blocked it was formed in. In the older PLC families it is sort-of possible.

Also (when mentioning later TIA-PLC combinations) the variables declared as "CONST" variables inside a code block, are also not available everywhere. But "CONST" is not an actual parameter but rather compile/software feature (as far as I know). 

 Details William, details...  By the way, thanks for the explanation for constants!

William

As a forum note: SCL published under the "Step7 Additional Software" heading is meant as the SCL add-on package for Step7 V5.x.

 Actually I've always wondered what does "Step7 Additional Software" mean to be honest . Now would you please give me the link from where I can download SCL add-on package?

William

No malice meant with the above text.

Regards,
w

 Non taken! 

Best regards,

Janko

jankoslayer

 Now would you please give me the link from where I can download SCL add-on package?

Janko - always good to hear from you.

The SCL add-on is not for (legal) download.
It is software that you buy from Siemens.. there are other add-ons too.
If anything, this is a positive that we have included on TIA Portal.

It is best you talk to your drug Siemens dealer for more detail.

Regards.
w

Hi,

My sincere thanx to William and Microman for making me understand the same.  Anyway in the SCL code, I am good in accessing the real value from instance DB @ db164.dbd536.

This I was able to access via 2 ways. One of them is direct addressing (Ex,  In1 := db164.dbd536 ). And the other one is making use of WORD_TO_BLOCK_DB, where in DBNo and Offset are supplied via input pins.

Where I am stuck is, implementing the same via Any pointer. For Ex:,  I got to access the value of DB @ db164.dbd536 using Any pointer and store the real value at some temp variable in the SCL. Like wise, I want to write into DB @ db164.dbx244.0 using Any Pointer.

Need some assistance to build this code please.

Regards

Nil

Hi,

Nil

Where I am stuck is, implementing the same via Any pointer. For Ex:,  I got to access the value of DB @ db164.dbd536 using Any pointer and store the real value at some temp variable in the SCL.

 I'm not entirely sure what are you looking for, but Any pointers are used basically for copy/paste of large amounts of data... If you have to do it inside the same DB (instance or glob) and you have to pass only few variables, you might reconsider using Any pointer... Working between various DBs actually makes sense. Anyway, in every possible case, you will always need two any pointer variables, one that stores the address of data of your choice and the other one that holds the address of memory where you want to put you data... 

Nil

 Like wise, I want to write into DB @ db164.dbx244.0 using Any Pointer.

 The same as in case before.

You cannot simply create one Any pointer that points to some var and then assign it to another type:

int something := AnyPtr(which points to some int) <== to the best of my knowledge this cannot be done.

Please read the second link in MicroMan's post, where Smiffy explains how to construct Any pointer, once again. I've learn from that thread the whole concept of any pointers.

Janko