Melsec FX3G communication with .net

All,

I am new to Mitsubishi PLC. In our project we need to communicate with the FX3G PLC using the USB port in PC. My program will be in C#/VB.net.

I have downloaded some protocol specification of FX series PLC. But all this specification is of Serial port. Can any one suggest how can I implement the communication/ How can I access the FX USB component?

Thanks,

Manish

I looked at doing this a while ago myself, but changed my mind and eventually added an E-NET module to the 3G and communicated via Ethernet instead (actually it was a good move because the industrial PC was eventually moved to a position far in excess of the USB limit). There are good examples to follow in the communications manual. I coded a quick interface in c# and found it relatively painless (and I am by no means a c# expert).

Thanks Twocozz,

Your suggestion is good, but actually we don't have any budget for that expensive hardware. BTW, what is the protocol used to communicate over ENet?

Regarding FX3G you have few options:
-classical FX3U-ENET - Ethernet communication module 10/100BaseT, TCP/IP, UDP, POP3, SMTP. Limitation is that you can't access to port 502, and that is standard port for modbus communication. Still you can do some tweaking if you have good router and have Modbus. Price around 450EUR. Excellent solution.
-FX3U-ENET-P502 - It has everything including Modbus TCP/IP. Price around 550EUR. This is the best solution regarding quality.
-FX3U-ENET-ADP - Mounted on the left side. Ethernet ADP module, MELSOFT, MC protocols, direct connection & data monitor. You can't do Modbus. Price around 200Eur. Very good solution if you have OPC or SCADA with drivers.
-FX3U-485ADP-MB. RS485 adapter with integrated Modbus support. Price around 180Eur. If you don't need high speed and you are not experienced programmer, but you still need equipment for harsh environment this is choice.
- FX3G-485-BD. Interface module mounted on front of PLC. Like previous but with this you need to have good programing skills. Price around 50Eur. After ENET this is my weapon of choice.
-FX3G comes with RS422 port. Do some programing and finish the job. Problem is that good RS232 to RS422 converter or USB to RS422 converter cost as much as FX3G-485-BD and you loose port for online monitoring.
-And last there is USB port, but USB is not solution for industrial environment. Forget about that.

Best regards.
Goran.
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Dear Goran,

Thanks for elaborated reply. That will be really useful info, especially when we will be developing a new solution. Actually in the current project, we are tasked to migrate a test application(VB 5.0) running on WinXP, which communicates with FX3G PLC to Windows 7 environment. The existing application is connected to the PLC using USB port and is using a COM(I guess) component FXCPUUSB to communicate with the registers of the PLC.
One thing which we don't need to do is "Changing the PLC program". I think with this restriction, option of using Modbus based hardware module(I am not too sure if the existing registers can directly mapped with Modbus option). All ethernet options are really expensive and customer does not want to spend much on migration activity. And as far as connectivity, the PC is pretty close to the PLC and the application is for EOL test application, so Customer is ok with continuing USB port alternate.
We are OK programmers to programe in C#, the only thing is that we have downloaded the protocol, and there are two points:
1. The protocol specifies only the serial commuincation(don't know how can I use USB connectivity PC(USB)-PLC(USB)).
2. There are two versions of protocol: one is with ASCII codes like BR, WR etc, and the other one says register address to be multiplied with 2 and convert to Hex and then ASCII. Really confused which communication is suitable for our device.

Please suggest.

Mansih

The protocol I used was the MC Protocol. I used "A compatible 1E frames" simple because all Mitsubishi PLC's support it (although you are limited in the size of block data you can send and receive in one go compared to other formats).