Communication protocol for Mitsubishi F1 series


Thread Starter

Lino Marques

I need to communicate with an old Mitsubishi F1 PLC.
I have some experience working with the FX series, but I have no experience or documentation of the F1 series.
I will appreciate if someone could send me the following information:

1) The default serial port configuration (baud, number of data bits and parity)

2) The frame format for the following commands
Send byte(s)
Read byte(s)
Force device

3) Address memory map, namelly the addresses of the following devices/registers

Thank you very much,
Lino Marques
[email protected]

Colin Carpenter (UK)


I'm afraid you're going to have a fair number of problems with your comms to an old F1.

To communicate with the programming port of the F1, you need two pieces of equipment. The normal Mitsubishi SC-03 lead (which converts from RS232 to RS422), which is used to communicate with (to my knowledge) all other Mitsubishi PLCs (FX,A1,Q etc), but you also need another interface unit
between that and the PLC. This is called a F2-20GF1 and fits onto the port of the F1 PLC. The SC-03 then plugs directly into it. The normal comms settings in Medoc is 19200, 8 , Even, 1 , but this has to match the comms dip switch settings on the F2-20GF1.

Your big problem will be getting hold of a F2-20GF1. They are no longer made, and are in big demand. My local Mitsubishi suppliers tell me that
they have 2 of them, and hire them out for £100 a day because they are so precious. The F1 (like all Mitsubishis) is pretty much bullet proof and
goes on for "ever", so there are still hundreds out there working away quite happily.

The F1 is very limited by todays standards, for example there are only 32 timers, and, more importantly, there are no data registers (Dxxx) in the PLC. The only way of using more than 32 timers that I know of, was to use the Mitsubishi "Step Ladder" programming, which allows multiple use of timers, as long as they are not in adjacent step ladder "rungs". And don't
use counters in step ladders rungs ...... seriously strange results.

Regards and good luck,

Colin Carpenter

Lino Marques


Thanks for your reply.

I already have a F2-20GF1 interface. The problem is that I don't have its manual.
My Mitsubishi representative doesn't have the manual also. They send me the manual of a similar interface (F2-232GF), but it seems that the frame formats are not the same. For example, when I try to read the PC type I send the frame {ENQ, '0', '0', '6', '0'}, but the interface apparently reply with garbage.

Do you (or someone reading this message) have the manual of the F2-20GF1 interface? I will appreciate if you could send me some information about the existing commands and their format.

Thanks in advance,
Lino Marques
[email protected]