FX2N-20MR chinese semi-clon of a Mitsubishi PLC and SCADA

[lwmar]

Dear all,

I have a FX2N-20MR chinese semi-clon of a Mitsubishi PLC. It has only a serial DB9 port that cannot be removed or exchanged (which is possible in the Mitsubishi original PLC). I wonder if I can make a simple SCADA system using that port and just one computer.

I am reading this post: https://forums.mrplc.com/index.php?/topic/9653-fx-series-and-modbus/

And I am wondering how I can do what it is suggested there in the second message: to use a free FB block, available in GX IEC (but not in GX Developer), which will communicate modbus via a standard RS232 BD board. Later on it mentions a library called ModbSFX. That message is from 15 years ago so I am wondering if now there is some other way to do it, perhaps some other software has that functionality? I don't have GX IEC.

I am a student trying to make a project so I would like a cheap and simple solution. Any help to do so will be very welcome.

Thanks
Regards

Marcelo

 

[lfe]

In the past there were HMI and SCADA screens with driver for the FX programming port.

I even programmed my own driver but I no longer have any information about it.

It is not a standard protocol and Mitsubishi never published it, I and probably others got it using reverse engineering.

I don't know if you can get any reference of that protocol

Besides, I always worked with real FXs, I don't know if the same would be applicable to the clone.

 

[parky]

The clone does not support the BD board, the on-board port will probably only communicate at 19600, Mitsubishi PLC has a default rate of 9600, however, Mitsubishi programming software is capable of requesting the PLC to change this up to 52kb (115kb on FX3U), the clones I have come across will not change, also, the clones I have seen you cannot change the PLC parameters so will not allow other important functions, basically, the clones have a limited instruction set almost complete but missing some important ones, even if the BD board could be used, you probably could not change to an open protocol.
I would imagine the programming protocol is the only one that would work, like has been mentioned, there is no data available on that protocol, well, not that I have found. Although the clones can be programmed with the Mitsubishi IDE's, the PLC only supports the general functions, even the analogues (for the ones that have it ) use the older RD3A instruction that is not used on the FX2/3 Range.

 

[lwmar]

Thanks for the replies. My PLC is currently working at 9600 bps. I've just found this document where it says the instructions supported (the one in the photo is a chinese semi-clon as well but with relays instead of optotransistors as mine). https://www.katranji.com/tocimages/files/349910-112013.pdf
Here it talks about another model but then the FX2N is mentioned as well in the text:
https://www.youtube.com/watch?v=disenZzqsjs
Is this last URL of any help to accomplish what I want to do?

 

[lfe]

... Mitsubishi programming software is capable of requesting the PLC to change this up to 52kb (115kb on FX3U) ...

I tried to find out how the Mitsubishi software was able to communicate at a higher speed and it does it according to this sequence:

- It first always connects at 9600 baud
- The software reads a pair of registers in the range D8xxx
- Based on the read values and using an algorithm that I never discovered the software calculates and writes two values to another pair of D8xxx registers
- From this point it can communicate at high speed

 

[parky]

Ife, you are correct, I too tried but TBH, could not warrant the time to delve into it any further, Beijers HMI's were also able to do this, then again they re-badged them for Mitsubishi so probably had inside info. If you set the baud rate in Mitsubishi IDE it stays at that speed until a re-boot or power up, then defaults back to 9600, one of the clones I tried (supposedly an FX3U) was set at 19200 & could not be changed, even GX software would not change it, I suppose that the vast numbers of clones out there all have differences, whether this is a modified OS or just not got some of the features of the originals is anybody's guess.
One other I tried, could not change the latch range again this is because it did not support reading or writing to the PLC parameters.