MB_server block: read more than 40126 blocks

Denilson Pegaia

Hi,

Here there are a sample project and some tips for implementation of MODBUS TCP with S7-1200:

1 - Pre requisites: STEP 7 >= V11 SP1 and S7-1200 FW >=2.1

2 – Documentation: the help on line of the blocksMB_SERVER and MB_CLIENTare the best way to get information about these blocks.

3 – Programming:

3.1 – On MODBUS TCP server

Use MB_SERVER instruction on the server:

Ports: as default you can use 502, however it is possible to use any ELSE ports already
used by S7-1200 (20, 21, 25, 80, 102, 123, 5001, 34962, 34963 and 34964).

Each connection needs a block call (with different instance DB, ID and port)

3.2 – On MODBUS TCP client:

Use MB_CLIENT instruction on the client:

Each connection need a block call (with different instance DB). ID and port must match with the server).

4- Status 7002 = meaning that there is no client connected.

 

 

NOTE: As from CPU FW4.0 / STEP 7 V13 SP1, the blocks MB_CLIENT / MB_SERVER was changed.

Now they are similar to S7-1500. The main difference is that now the connection definition is not made in block inputs but else in a external place (DB).

 

To create the connection reference DB, create a DB as usual, and as variable (any name) you should type (manually) as data type “TCON_IP_V4”.
The blocks online help shows the meaning of the variables.

I attached now two examples at one zip file: one for FW>4, other for FW<=3 (as original)

In the post of 28/04/2018 I place a V15 project version + cast showing the project steps.

 Hiii,

I have used MB_server block for Modbus tcp holding register reading , but these block have limit to read holding register from 40001 to 40125 but i want to read more than 40126 but block give error 

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Split from Tips and sample program for MODBUS TCP.