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  1. #1
    Member
    Join Date
    Sep 2021
    Posts
    3

    Fanuc 21-T dead rs232 comms

    Hello everyone

    I have a new to me Daewoo Lynx 200B lathe, I need some assistance in troubleshooting the RS232 Communications. The machine uses a Fanuc 21-T control.

    I would like to say I have tried absolutely everything under the sun to try and communicate with the machine but maybe I missed something.

    I have tried the following and a million combinations of Baud rates, parity, stop bits, flow control, cables, com ports, software etc.

    I cannot send or receive a single byte of information between the cnc and my pc.

    My setup is a usb to serial db9 cable that I have confirmed works by using it to send files to and from a different machine. I then use a custom made db9-db25 rs 232 cable that again has been confirmed to work.

    When I try to send files to the CNC, the leds on the usb serial cable blink indicating transfer is occuring but I dont believe that any data is being recorded by the cnc control. The menu on the Fanuc display blinks LSK like its waiting for data but nothing comes through. I have also tried sending a file from the machine to the control but again nothing comes through. It seems to me that the Fanuc board may just be toast. - as far as I know this machine came out of a running cnc shop.

    Any suggestions?

  2. #2
    Member
    Join Date
    Sep 2021
    Posts
    3

    Re: Fanuc 21-T dead rs232 comms

    If it helps anyone in the future.

    I discovered that I needed to have my cable cross pins 2 and 3 instead of 2-2 and 3-3.

    No idea why this machine is this way. But I can now send files to and from.

  3. #3
    Registered
    Join Date
    Mar 2015
    Posts
    36

    Re: Fanuc 21-T dead rs232 comms

    Greetings,

    Your solution brings a FlashBack to me.

    Years ago I had a flatbed plotter that used a "Null" Modem cable.

    I bought a box of connectors and a crimp tool to make my own cables.

    Like you, I do not know the electronics well enough.

    Cheers,

    Dave

  4. #4
    Registered
    Join Date
    Apr 2011
    Posts
    823

    Re: Fanuc 21-T dead rs232 comms

    Quote Originally Posted by Jeremy_Sawatzky View Post
    If it helps anyone in the future.

    I discovered that I needed to have my cable cross pins 2 and 3 instead of 2-2 and 3-3.

    No idea why this machine is this way. But I can now send files to and from.
    Because pin 2 is send data and pin 3 is receive data. You were trying to send to a "send" signal.

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