Hi,

I’m working on an old existing S7-300 project and need to send alarm data to an HMI using Modbus communication through CP 341 communication processor. Could you guide me through the process of Modbus mapping to achieve this?

Specifically, I need help with

1. Mapping alarm data from the S7-300 to Modbus registers.
2. which type protocol need to select (eg: ASCII,RK512,3964(R),MODBUS MASTER OR SLAVE)
3. can I use ASCII to send alarm data to HMI?

Any tips or resources you could provide would be greatly appreciated.

Hello

Should the third party HMI Device act as Modbus Master or Slave?

If the PLC should run as master you can have a look at this example:

https://support.industry.siemens.com/cs/ww/en/view/109474714

Bye Murof

Thank you for your time,

We need Modbus RTU slave communication from the S7-300 PLC to send alarms to a master device. Do I need to purchase a Modbus RTU slave license for the CP341?

Are there any other options for Modbus RTU communication with the S7-300?

How do I map the alarm data from the PLC to the CP341 in TIA Portal?