MODBUS TCP on X20 CP1584 PLC

Hi,
im not able to read/write data over modbus TCP.

Ive added the Modbus TCP Any object in Eth and configured required settings in the object.

kindly assist further setting to communicate modbus TCP

Hi Sandeep,

We will need some more information before we can help you. Can you please give us some more details about what you’re seeing? Are you getting error numbers or log messages? “not able to read/write data over modbus TCP” is not enough information to go on.

Hi,

1: Network diagnostics
To check the network settings or the network connection to another network participant, it is possible to send a ping from the B&R controller. The AsICMP library is available for this purpose and includes an example:

If the other party cannot be reached via a ping, the Ethernet settings and the network must be checked.

2: Modbus TCP Client diagnostics

If you configure a Modbus TCP master, a Modbus client is activated in the operating system. This makes logger entries. It is therefore interesting to see whether there are entries for Modbus TCP in the controller logger.

3: Settings
To check the settings, the B&R support department typically always requests the entire Automation Studio project. This way, all settings can be viewed in full.

4: Configuration of the Modbus registers
To configure the registers correctly, a good data sheet for the remote station is helpful. Is there one?

5: Test with another client.

There are Modbus TCP freeware Windows clients. These can be used instead of the controller for a simple test. These can be used to rule out network problems and verify the register addresses. These tools are usually faster for testing.

6: Network trace
I only recommend a network recording if points 1 to 4 are not sufficient. Tools such as Wireshark can be used for this.

Best regards Stefan