How to sovle the problem like this- Fanuc OMD

[thanhct]

Dear All.
I'm using DNC Lan to send NC programe from PC to CNC.
My old CNC control is Fanuc OM. The alarm is 087, buffer overflowe.
I've try to leave fifo buffers checked and reduce the transmit buffer to 1. But still not yet sovled this problem.
Port setting: 9600 baud, 7 data, 1 stop, even parity.
Flow control: Xon/off.

Could You help me to sovle this problem.
Thank You for your looking.

[timlkallam]

I sounds like your pc is sending the program to the machine faster than it can handle.I had the buffer overflow alarm and my dnc software as a setting were the program will pause between blocks .

[TheePres]

Thanhct,
I am not familiar with DNC Lan, but check for settings similar to this:

{Transmit--Data Packet Size} Set to 9
This only for Fanucs

[dcoupar]

Are you using a USB to Serial adapter? These are notorious for not handshaking well. I've had better luck with a standard com port (if available) and if not, a PCMCIA RS-232 adapter like Quatech.

Even with a standard com port, I've had to set both the Transmit and Recieve buffers to 1, and then UNcheck the Use FIFO buffers check box.

Also, how long is your cable, is it shielded, and the shield tied to Pin 1 on the machine side?

If all else fails, slow your baud rate down to 4800, or even 2400.

Good luck.

[notallhere]

Set Flow control: Xon/off. to none our 0MD wont send or recice set to on/off

[Dan Fritz]

Your DNC software isn't responding to the Xoff fast enough. This is a big problem with many DNC systems. The Fanucs can only accept 10 characters after the Xoff, so the software has to respond very fast when the Fanuc's buffer gets full.

Some serial port device drivers can be configured to handshake automatically with Xon/Xoff characters. Some other device drivers SAY they use Xon/Xoff, but they don't work very well (or at all). If the DNC software is written to do all the work of handshaking, it may be too slow for the Fanuc control. It's always best to use device driver handshaking whenever possible.

We write our PC-DNC Editor and PC-DNC Plus software so that you can select device driver handshaking or not. If you use the device driver, the DNC software just tells the device driver to respond to Xon/Xoff, then it sends lots of data to the device driver. The DNC software may be several thousand bytes of data ahead of the device driver, and all that data is held in a buffer.

If the device driver is not up to the job, you must turn off device driver handshaking and let the DNC software put only a few characters at a time into an output buffer. The DNC software must then "listen" for the Xoff signal after every few characters is sent, so that the output buffer never contains more than 10 characters. Our software can do this, but many DNC programs written for MS-DOS can't. MS-DOS programs frequently use a 128 byte "file" buffer to output to the serial port (just like outputting to a disk file), which makes handshaking very difficult. The only solution with these kinds of DNC programs is to put a time delay between every character, or slow the baudrate down to an unacceptable level.

If you can try this experiment, it might tell you something:

Connect two PCs together using your DNC software on one PC and a "terminal" program on the other PC (like Hyperterminal). Configure the DNC software to send using Xon/Xoff, then type a Ctrl + "Q" on the terminal PC to begin the transmission (Ctrl + "Q" is an Xon). Then, as the data is streaming from one PC to another, type Ctrl + "S" (Xoff) and see if the DNC computer stops right away. It would be normal to see a few characters after the Xoff, but more than 10 means that you're in trouble with the Fanuc control. Good serial port device drivers should stop within 2 or 3 characters at 9600 baud.

[Mitsui Seiki]

We had a similar problem.The same alarm.
The machines buffer was too small.We had to send the main progam first and then the subprograms separately.The file was too big.

[thanhct]

thank you all.
I've solved the problem. I changed the controller's parameter and checked out the conection.