HMI Communication with SIEMENS PLC


Thread Starter

Ali Shakarami

In GE HMI of gas turbine generator, I want to send some signal value to another system (PLC SIEMENS) via modbus RTU. I found that in the HMI (Cimplicity) I can set up this communication to sending these signals but I did the configuration via COM1 but in the status of the port COM2 is "halted".

* Can I send the signal from HMI to others controller by MODBUS at all?

* If yes. How does it possible?

It will be appreciated for any help.

PLC Programmer

The answer is yes. You can transfer signals over the modbus with your HMI.

The problem is that Siemens does not use Modbus communication but Profibus/Profinet based communication, which is a patented communication system for Siemens alone.

There is a solution though. You can use an OPC server between the PLC and HMI. This helps map the signal from the profibus to Modbus and vice-versa.

You'll have to research on Profibus and its conversion to Modbus.

Hope that answers
Siemens developed Profibus and Profinet, but they are not patented. Actually GE (which is the manufacturer of Cimplicity and a major competitor of Siemens in many fields) uses Profinet:

In addition, some configurations of Siemens PLCs can work with the Modbus protocol: modbus/tcp

<b>Moderator's Note:</b> When copying and pasting long URLs, make sure you copy the entire URL and remove any spaces the forum software places in the URL.

Maybe someone with more experience on this field can confirm it, but configuring Modbus should be easier with the new S7-1500 rather than with the old S7-300.

If you don't want or can't modify your PLC, you can follow the advise given by PLC Programmer in the previous post. This is the same philosophy that GE uses to communicate its MarkVIe controller (EGD) and its Cimplicity software (OPC), by means of placing the OPC server of its ToolboxST software in between.

You could use an OPC server that reads the Profibus data and converts it to OPC, then the Cimplicity software would read the OPC data.

There's a famous and reliable OPC server starting by K* that can do this, but if you search a bit you may find others.

Patrick Lansdorf


You will need to check what type of Siemens PLC it is. If it is S7-1200 or S7-1500, you should be able to use Modbus RTU straight off, as they support it.

But, if the Siemens PLC is S7-300 or S7-400 - The cheapest and easiest solution is to use a gateway.
If the HMI is a Modbus Slave, the gateway needs to be Modbus RTU master and If the HMI is Modbus RTU master, the gateway needs to be Modbus RTU slave.

I work for HMS and we have a huge variety of gateways.

My 2 cents