Unable to reconnect Fanuc 420i rj2 to the pc (using kfloppy)

  • Hi,

    I had my Fanuc 420i rj2 connected to the pc (using kfloppy), and it work fine... last week i saw that with a vfd(spindle) on there were interference (electric noise) and the connection brake. But when turning of the spindle of the connection between controller was fine... until this week.

    Now the connection between pc and controller doesn't work any more, i try everything i could think of,

    - I check the cabe with a multimeter to see if it was working, and it was ok,

    - i try to configure and connect through port2 using the same rs-232, dint work,

    - i reinstall the dosbox and kfloppy files, dint change...

    Question don't know if the electric noise made by the vfd demadge something... is it possible?

    Can anyone help me, i really need to put that robot to work and fast....



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  • Are you using a cable made to work with kfloppy? You should not use a normal RS-232 computer cable that connects all 25 pins. Fanuc has +24VDC on pin 25 of their RS-232 port that they use to power peripherals like the PS-100 disk drive. Pin 25 on a normal RS-232 is a ground. Connecting a standard computer cable between the robot controller and a computer can do damage to the COM1 port on the computer.

    Here is the official cable pinout:

    When you reloaded DOSBox, did it overwrite the DOSBox 0.74-2 Options.bat file? If so, you may need to modify that file to work with your com port again.

    When you reinstalled Kfloppy, did you setup the Port and Emulator settings properly?

    If you use an USB-to-RS232 converter, if you change USB ports, the com port # changes.

  • Hi Skooter , greetings from portugal,

    Really appreciate your reply, do you have a similar robot and controller?

    Yes i have a cable that is wired exactly as the diagram you sent, thank you.

    I dont know if i was clear but i'm working with robot/pc connection on the last 6 month, without any problem.

    The problem is that after start the emulation pc/robot, there is no activity registed on the kfloppy, and there is a timeout message on the teachpendant...

    i don't know is the electric noise made by the vfd damage the port 1 of the controller... or if it was the com1 of the pc.

    Tomorow im going to try another pc (with serial port), to test if it from the pc or not. i will be happy if the com1 as a problem and not the controller...

    if that doesn't work i will recheck if the cable is fully function..

    i will see how is the Options.bat file...

    Question do you think electrical noise made by a vfd could damage something on the controller?

    Thank you!

  • Since you're using DOSBox, I assume you are using Win7 or Win10. Which version is it?

    I also have to ask if you made sure the device selected in the file menu is set to 'Floppy Drive'.

    Regarding the VFD noise, I wouldn't expect that to be an issue unless the Kfloppy and the drive cables were running parallel and the Kfloppy cable was unshielded.

  • Hi Skooter

    I was using windows 7, but a friend is trying to set a Windows XP to run some tests.

    yes i selected floppy drive. There is thirth option in the UTIL menu, that i don't remember the name, when i choose it and make DIR and enter it show the content of another disc or memory with .SV files and some tp. Because it access this third memory like the kfloppy (presents the message - accessing device and in a second present the content of the third memory appears). I guess the hardware on the controller that make the connection is ok.

    I made the test, the vdf must be far from the controller and pc.

    I bought some ferrite bracelets to increase the shield of the cable. Got the idea from this video

    i already bought terminals to redo the cable if is needed. Im not that great on welding cables..…6f8ca31ffe294d7%7Ciid%3A1…6f8ca31ffe294d7%7Ciid%3A1

    Thank you

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