Hello everyone. Thanks for taking the time to read my question.

I would consider myself a advanced-beginner PLC programmer. I've used the Siemens 1200s fairly regularly.

Here' is my dilemma. I've created a program that uses a 1200 and a touchscreen. My client now wants to be able to access as many functions from the touch screen as possible using Modbus. I've never used Modbus, but I've researched quite a bit and have actually set up 2 1200s passing DBs to one another using the Modbus Master/Slave blocks in order to get some understanding on how it works. The main problem is that my client will not be using another PLC, but a 3rd party HMI software to monitor and set values. I've set up my PLC to act as a slave, but how do I address everything so that he may write/read values in my PLC?

Does this make sense?

Thanks again for your time and help.

-=coasterbp

 

Many HMI's are Modbus masters. Assuming the one you'll be dealing with is a Modbus master, you'll just have to work through the specific programming that brand HMI uses as a Modbus master.

 

Yes, their system will be the master. I need to know what I need to do on MY end, the slave side, (the Siemens 1200) so that they can access/write data to it. I have the function blocks set up as a slave, but don't I need to address the data in a certain way?

Thank you!