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Topic:   Fanuc - Buffer Overflow (Partial Transfer)

By: HKPosted on: Nov 21 2007 at 04:42:05 PM
I`m getting a buffer overflow when using 4800, 7, E, 1, Xon/Xoff, 25ms.

The machine always receives 29% of the program (this depends which program we try to send and what size it is, it receives all of the small ones).

Changing the BAUD rate to 2400, 1200, etc. results in a "Invalid Frame Rate" error.

This same problem happens on two different machines, each one having different cables running to them.

We`re using some very long DB25 cables. If the cables were bad would the machine bomb out at the same place every time?

By: SupportPosted on: Nov 21 2007 at 06:25:00 PM
If your cables are long or low quality and/or routed along by other electrical wiring or equipment which is generating magnetic fields then you might get data errors - not buffer overflows. And even then it would not cause the transfer to fail in the same place every time, it would be random.

Buffer overflpw is caused when the data is going in to the CNC faster than the CNC can handle it. Flow control (XonXoff is supposed to control the flow of data and prevent buffer overflow but modern computers are very fast and sometimes xonxoff flow control is just not efficient enough to stop the fast computer from sending too quickly. (The fast computer sometimes ignores flow control signals from the CNC)

Only resolution is to slow down the baud rate and/or increase the block delay in easyDnc (also search the forum for posts about FIFO)

By: HKPosted on: Nov 21 2007 at 07:11:45 PM
I did increase the block delay to 125ms and also changed the FIFO to 1 and then disabled FIFO entirely. Everything is working fine now.

Thanks for your help.

By: GuestPosted on: Nov 16 2016 at 11:16:40 AM
SR 834 buffer overflow

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