Hi,

I have used an example project named MODBUS_PN_CPU, as a server and as a client, because I have both scenarios in my project.

When trying to test software as a client, I can not manage to exchange data between PLC and my touch panel (server).

From the example project, I have only changed the IP address in the MODBUS_PARAM DB block (entered IP of my panel).

When I run the variable table, I tried to write (read) from address 40001 on my panel, so I put in my variable table address DB11.DBW1 (tried also and DBW0).

DB11 in the example project is for holding registers, starting from 0.

Online, there is no error in the MODBUSPN block (except a090 for licencing).

Any tip would be very helpful...

Hi,

what is shown in Save_STATUS? The output parameter STATUS is valid only 1 cpu cycle and so it can be, that you can't see the error message on STATUS.

What do you set to the runtime parameter START_ADDRESS and LENGTH?
Notice, that Holding Register 40001 is address 0 in the modbus block. 40002 is address 1. (It is also described in the manual). Wenn you parametrize start_1 = 0 in the parameter datablock and set START_ADDRESS = 40001, then the error code is A006.

Wüstenräuber

Hi,

thank you for your replies.

Actually, I have tried with START_ADRESS both 0 and 1. But nothing changed.

You can see the var table in the picture attached.

I have managed to communicate with the touch panel via the Modbus poll...

I forgot to mention when I put ENQ_ENR to 1 (he also stays false), nothing happens.

Now I'm getting busy all the time, and Save_STATUS is a100...

I can not manage to trigger ENQ_ENR also.

Now I'm getting busy all the time, and Save_STATUS is a100...

I can not manage to trigger ENQ_ENR also.

EDIT: I solved it... Can't believe it, but problem was that the IP address of the server entered in the MODBUS_PARAM block was not initialized... When I compared Initial and actual values, it was different...

Thank you all for trying to help.

Anyway, I would like to know, why entered parameters in the Initial value weren't accepted in the CPU after downloading the block?

Thank you! That helped me a lot.

One more question, if you don't mind...

In the MODBUS_PARAM block, where I define DB's for data (1-8), can I have the same START_ADRESS for different DB and different data?

For example:

ID1_data_type_1 B#16#3

ID1_db_1  W#16#B

ID1_start_1 W#16#0

ID1_end_1 W#16#1F3

and

ID1_data_type_5 B#16#1

ID1_db_5 W#16#E

ID1_start_5 W#16#0

ID1_end_5 W#16#4

Because I'm facing a problem when I change start_adress in MODBUS_PARAM block. Coils in the example program start from address 640 (and that is working fine), but I need to read the address from 0. When I change it, initialize and download block, I'm getting error A006.

I noticed also, even after I changed the start address, I can read from an address that was defined in the example program (640).

Wüstenräuber

Hi,

yes, of course you can use the same start_x addresses for the different data areas. The data areas are like drawer with little boxes inside: each drawer has a first box, a second box etc.
So there are holding register 0, 1, 2... and coils 0, 1, 2...

For coils you parameterized address 0 to 4 in data_area_5 and #6A4 to #8FC in data_area_7. And then you try to read address 0, length 32 (#20). But coils 5 to 32 are not defined in the parameter datablock.
You must set end_5 = #20 or higher.

Wüstenräuber

Thank you very much for the explanation, like a teacher :)

About my example, sorry for the bad values for the end address, I was trying something. Here is a new picture, where you can see that length is lower than the end address... But still no changes.

Interesting thing is that I can read/write when I put the start address from data_area_7 (6A4)...

And also, even I changed these addresses in data_area_5, I still can read/write when I put start address 640 (which was by default on the example program).

Hi,

If you mean (visible from var table) on DB1.DBX28.1, I tried to set it on true, but nothing happens.

Wüstenräuber

Or check, that CONTROL_DAT.Init it set to Init parameter of the modbus block in OB1 (or other cyclical OB). And for the initalization you must set ENQ_ENR = FALSE. 
Do you have an entry in Init_Status?

THANK YOU! THANK YOU! THANK YOU...

That was exactly the solution to my problem.

Wish you all the best.

Kind regards,

Petar