Hi,

I have been trying to establish a MODBUS TCP connection between a LOGO v8.3 and an Arduino Mega with EN28J60 Ethernet Adapter for a whole day but with no success.

Basically my goal is to be able to extent my LOGO I/O utilizing the Arduino Mega board. For example, if I set a network output on the LOGO, the Arduino should set the corresponding digital output on the board. Or if I have a TRUE value on a digital input on the Arduino, the LOGO should see its value via a network input.

I do not know if this is possible at all but I was trying to make at least the output part of the LOGO and Arduino to work.

Here is the library for MODBUS TCP on the Arduino side:

Arduino MODBUS TCP Library

If you could give any suggestions on how to continue approaching this problem, I will appreciate it.

Best Regards

Konstantin Kolev

 Hi,

I attached a picture with some of my settings a test program.

The input is a simple switch with a NO contact attached. For testing purposes on the Arduino side I programmed a blinking LED with different frequency depending the state of the switch that is input on the LOGO side.

I am not sure if the MODBUS settings (LOGO as a server) is correct. By the way the library for the Arduino side MODBUS states that it can only work as a slave. It is a bit confusing what they mean with "slave" - a client or a server?

ixo65

Show us your try ....

 Therefore the LOGO controller is a client of the Arduino board which means that the LOGO side can only request information from the Arduino, for example, reading a potentiometer connected to the Arduino analog input.

But is it possible to send data from the LOGO to the Arduino side? For example, let us assume we have a PROFINET devices - a controller and a device. They can both communicate to each other - the controller sets outputs which can be seen as inputs on the device and vice versa.

ixo65

Slave = Server
Client = Master

Hi,

you have configured LOGO! as a Modbus Server. If you riectly need to read/write I/O's in LOGO! you don't need to use VM-memory in LOGO!.

So you need to configure the Arduino to read DI1 from LOGO!. In this case you directly read the status of Input1 from LOGO!.

To control output 1 in LOGO!, just set coil 8193.

The unit ID for LOGO! should be 255.

In LOGO! you need a program to switch LOGO! to RUN Mode. 

Hope this helps

 Hi,

Thank you for your response.

Actually my main purpose is to set/activate digital outputs of the Arduino from the LOGO. Let us say, for example, I set a VM bit  in the LOGO which the Arduino can read as a MODBUS coil. I am not sure if that is the correct way to do it, though. I will have some more time to do experiments in the weekend.

Best Regards

Konstantin Kolev

AutoGen_380038

Hi,

you have configured LOGO! as a Modbus Server. If you riectly need to read/write I/O's in LOGO! you don't need to use VM-memory in LOGO!.

So you need to configure the Arduino to read DI1 from LOGO!. In this case you directly read the status of Input1 from LOGO!.

To control output 1 in LOGO!, just set coil 8193.

The unit ID for LOGO! should be 255.

In LOGO! you need a program to switch LOGO! to RUN Mode. 

Hope this helps