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or misuse of techniques shown in this web page. We simply publish information
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Using Standard And Inexpensive DNC Software
Three Gems For Program Storage & Retrieval By Ronald Walkenhorst of
AccuCraft, New Haven, MO
I read your fine article about distributive numerical control in the
September 1994 issue of Cutting Tool Engineering and thought you might be
interested in hearing about the simple setup we use in our "mom &
pop" shop (grand total of one machining center) to send programs back and
forth between our CAD/CAM system and machine control.
We've always had a serial cable linking the two, but the DNC part of our
CAD/CAM system was cumbersome. I also had to spend a lot of time running back
and forth between the machining center and the office when sending programs,
which is about 50 feet away and up a long flight of stairs. I'm sure the
exercise was good for me, but it wasn't a very efficient use of shop time. Two
little gems solved the problem for me, and I can't believe how simple and
inexpensive it was.
Gem number one is a device called PC Companion Plus, manufactured by Cybex
Corporation of Huntsville Alabama (ph: 205-534-0011). It costs about $500.00
and consists of two small boxes and a cable that allowed us to hook up a remote
monitor, keyboard, and mouse for the computer that the CAD/CAM system runs on.
Now we have a computer work station in the shop and about ten feet from the
machining center, with the original monitor, keyboard, mouse, CPU, and printer
remaining upstairs. The CPU pays attention to whichever keyboard/mouse is being
This is much less expensive and complex than setting up a network and the
speed of the system has not been degraded as I'm told it would have been with a
network. Another advantage is that since there is only one CPU, we didn't have
to buy network licenses for our software. When we replaced our old CNC machines
with a new Haas a couple of years ago, the installer and I couldn't get the
"pain-in-the-neck" DNC software from our CAD/CAM system to work with
our new control.
We jury-rigged another communication software to do the job until one day I
stumbled across gem number two, which had been right under my nose all along:
the "Terminal" communications program that comes free with Microsoft
Windows (version 3.1). Once I got the baud rate and everything else in Terminal
set up to agree with the Haas control, I saved the settings in a .TRM file (I
called it HAAS.TRM). Then I drug a copy the terminal icon from the Windows
Program Manager Accessories group (where the windows installation program had
put it by default) over to my CAD/CAM group, which is where we have all the
icons for our CNC related software. Then I changed the icon to say Haas DNC
instead of Terminal. In the properties for the icon, I added HAAS.TRM to the
end of the command line and made the working directory the directory that the
CAM system puts CNC programs when it posts them.
Now when I double-click on the Haas DNC icon, the Terminal program starts
and the communications settings in the HAAS.TRM file are automatically loaded.
Since the CNC programs are already in the specified working directory, they are
automatically listed when I want to send a program. The procedure for sending a
program from the PC to the machining center goes like this: On the machining
center control panel, I press "List Programs", cursor down to
"All", and press "RS232 Receive" (the actual procedure for
Fanuc controls will be slightly different). Then I step over to the remote PC
station, double click on the "Haas DNC" icon, click transfers, and
then "Send Text File". A list available CNC programs appears. I
simply double click on the one I want to send. Total elapsed time for all of
this is about fifteen seconds. Sending programs back from the Haas is similar.
As long as the program already exists, everything is done with mouse clicks;
there is no need to type in file names or any other information. Though we only
have one machine, communicating with more than one machine would simply require
adding a card or cards for more serial ports in the PC (it seems to me that
this would be preferable to, and probably not much more expensive than, an
A-B-C manual switch box). You could make as many copies of the Terminal icon as
you wanted and customize their properties (in the way I described) to suit the
various machine controls with which you communicate. You could also easily
assign each machine its own special subdirectory of the computer's hard drive
for program storage and specify its particular COM port number within the
icon's properties. With our Haas, we have also successfully sent the machine's
parameters and other settings to the PC as a .TXT file. This will come in handy
some day if the control's battery goes dead. I have one more gem for you.
Gem number three has to do with how we enter type manual programs. I have
trashed the balky text editor that came with our CAD/CAM system in favor of
Word for Windows, which I have customized for CNC program editing with a few
macros I wrote in WordBasic (the Word macro language). Now a few mouse clicks
zip me through a program and perform editing tasks that used to take much
longer. One of the macros extracts certain information from the CAM system,
like estimated cycle time and material data and adds it to the end of my CNC
program in the form of comments. It also prompts me for other information, like
customer name and workholding methods, which it also tacks onto the program. We
no longer use a paper setup sheet since all information needed to run a job is
right in the CNC program!