Hi guys,

I'm trying to using the MB_SERVER function of modbus in another way,

I need to be able to read 2 dbs at the same time; so i changed the "ID" parameter in the instace db of each function (called 2 times) and marked it like this:

DB1 (first db that must be readed) as ID "1"

DB2 (second db that must be readed) as ID "2"

and called the function 2 times, in the orded that i wrote just on top.

But unfortunately when i select the id from the client i can even read only the first DB1, i can't read another db by changing this parameter.

If i swap the function calls i can read only the second db.

Is possible what i'm trying to do? (the siemens consuelor says yes...)

What's the correct way to do this?

Thanks u prevently for any help!

hi,

yes it should work. 

did you call the MB-Server-FB with 2 seperate Instances?

Please post some screenshots of your calls. 

regards,

hmm...looks okay.

The TIA-Help says also, that it should work

Description of MB_SERVER

Multiple server connections

You can create multiple Server connections. This allows a single CPU to accept connections from multiple Modbus TCP clients at the same time.

A Modbus TCP server can support several TCP connections and the maximum number of connections depends on the CPU being used.

The total number of connections of one CPU, including those of the Modbus TCP clients and server must not exceed the maximum number of supported connections.

Modbus TCP connections can also be shared by "MB_CLIENT" and/or "MB_SERVER" instances.

In the case of Server connections, remember the following rules:

• Each "MB_SERVER" connection must use a unique instance DB.

• Each "MB_SERVER" connection must use a unique connection ID.

  The relevant individual connection ID must be used for each individual instance DB of the instruction. The connection ID and instance DB belong together in pairs and must be unique for each connection.

• For each connection, the "MB_SERVER" instruction must be called individually.

hi marco,

what about the CONNECT-parameters?

Can you post them like the calls?

regards,

Hello Marco,

Did you try to disconnect the correct MB_SERVER to see if the second one work?

Best regards,

Hugo

Hello again guys,

That's the configuration of the first DB executed, in the next answer i'll post the second.

And there is the second DB executed.

Yes i tryed to delete the first one and discovered to can read only the first executed DB.

So if i execute them in this order,

MB_SERVER > DB1

MB_SERVER > DB2

I can read only the DB1, also if i change the ID in the parameters.

if i swap them i can read only DB2, even if i change the ID in the parameters.

and if i delete it's the same story.

So, i am probably thinking that i send as ID from the client the wrong parameter then it's not possible read multiple DBs from a single CPU by changing this "ID" setting.

hi, 

have you tried to use different ports?

regards,