BTR / Fanuc tape drive interfaces

Hi group,
Many years ago I have made a connection for Fanuc 5 to PC and it works
well Fanuc 5 and 6. I have not tried personnaly on Fanuc 7, but it
should work, as far as 7 was released between 5 and 6.
Although the program works well without any buffers, the bad experience
shows, that the buffer board (files section, BTRFANUC.JPG) saves the CNC
or PC when a ground loops exist on some workshops.
Used signals are RDT - reader ready, thats the switch on it on AUTO
position, FDT - feed forward - CNC asks data, 8 data bits and strobe. On
the schematic there may be error on buffering RDT, I will check
tomorrow, it is quite an old picture.
You can transfer a program in ISO or EIA format, but of course ISO is
simpler, beacause it is ASCII with som chars missing. Some CNC do not
like characters missing in the table, some versions just skip them. The
parity bit is usually necessary.
The protocol is simple: Put a byte on the output, issue 2.5 ms strobe,
wait 2.5 ms, put next data etc.
In fact, do the same what the real PTR does. The timing is critical,
because in FANUC 5 and 6 reading from PTR is by polling, not interrupt
driven. One can try from 2 to 3 ms. The problems arise better when you
try to upload a big program in CNC memory, because then CNC needs more
time for storing calculations - Fanuc 5 stores a char in 6 bits for
better memory use.
Best regards and hope this could be of use.
Fedia


_____________________________________________________________

>Message: 12
> Date: Fri, 30 Aug 2002 21:08:54 -0000
> From: "davebowl" <davebowl@...>
>Subject: BTR / Fanuc tape drive interfaces
>
>I'm looking for a cheap BTR (behind tape reader) for a Fanuc 7m tape
>drive (less than $200). But If I can't find one to buy I'd like to
>build one. The interface to the serial or parallel port of a PC is
>well know, but it's the pin out and interface to the Fanuc 7m tape
>drive that I'm missing. The unit I have has the 50 pin connector.
>I'm looking for pin out on the tape drive, signal names and timing
>information. I'm also intrest in the pin outs on anyother tape drive.
> I'd also like to know if there is any interest from other people for
>an inexpensive BTR for Fanuc and other older controllers. If there is
>interest, I'd like to try to market an open source BTR interface cable
>and software in the $150 to $200 price range.
>
>
>________________________________________________________________________
>
>

--
Fedia Buznik
fedia@...