SFB4 in shared Datablock possible?

Hi!

Is it possible to declare several SFB4 (TON) in a UDT and then create several DB of type (from our UDT)?

I was hoping not to have them stored in a instance datablock for an FB (in the STAT Area)...

Best Regards

Unfortunately you cant do that directly.
UDTs, shared DBs, or derivatives thereof cannot be definded from the declarations of FBs or SFBs.
The best I can suggest is to use multiple-instance FB+IDBs.

I am sure though that LD can find a way to do it for shared DBs with some clever pointer addressing.

edda said:

Is it possible to declare several SFB4 (TON) in a UDT and then create several DB of type (from our UDT)?

I was hoping not to have them stored in a instance datablock for an FB (in the STAT Area)...

Best Regards

Click to expand...

More explanation required. As you can define an instance DB for each call to SFB4, I fail to see the advantage or reason for creating your own global DB's to do the same job.

Thanks for your responces.


Okey, here is what I´m after.

Let´s say that we have a couple of blocks that are similar, let´s say 3 diffrent Motor blocks.

1. Ordinary Strait Motor.
2. Y/D-Started Motor
3. 2-direction Motor

All of these share some command / status bits to HMI/SCADA.

Let´s say: Auto/Manual, Manual-Start, SSW-Alarm, CB-Alarm, Running and so on.

I would like to have the same addresses for all block indipendent on the number of In, Out, In_Out of the block (because the Instance DB maps up everything in the datablock I get offsets in the start addesses of Stats depending to witch block it belongs to).

So I would like to use the same adresses of the shared bits only have to keep track of the DB number.

Very simplified in the attached image...

My plan was to create Shared DB with the data and passing a DB-number...

I would link only the HMI-relevant data to an IO-pin on the FB or FC.
You can define the data in both the shared DB and on the FC/FB IO-pin by a UDT. In that way you get what you want. It will be easy to maintain because any change to the UDT will permeate throughout the program.

By placing a complete structure (greater than 4 bytes) on an IO-pin, then all accesses inside the FC/FB to that data will be by pointer. Some will argue that it will then be not so optimal, but it is not so critical when it is only for the relatively few data that is related to the HMI.

edit: To return back to the original topic.
You can see by this that all of the data for the various SFB4 instances will not be linked to your shared DB. Only what you configure to be included in the HMI UDT.