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Setting the FIFO buffers to Low. |
Problem: When trying to drip feed, the CNC misses data or alarms out when running.
This is most likely caused by a handshake problem
Refer to the RS232 setup page in your control or to the CNC's manual for further information.
If you are running the server on Windows® 7, 8 or 10, and software handshaking is enabled, the server might not respond to and XOff request in time, and therefore overflow the CNC.
Go to Control Panel / System / Device manager / Ports (COM & LPT) / COM1 (COM2 etc) / Port Settings / Advanced , and set the receive and transmit buffers to low (1).
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Setting the FIFO buffers to Low. |
If possible, try turning the feed rate down to zero on the CNC. This should eventually stop all transmission until the feedrate is turned up again. If it does not, then the handshaking is not working properly.
Check that you are using the correct handshake method. If hardware handshake is not enabled, try selecting Set RTS high and/or Set DTR high in the serial port configuration dialog.
Some machines use non-standard software handshake characters. If this is the case change the XOn character / XOff character in the serial port configuration dialog.
For further information, please refer to Serial Port.
Some machines need a specific character before it starts to store a file. Check the machine manual. Many machines need a % at the top of the program, some need NULLs (blank tape), others need an end of block code (CR/LF).
If this is the case, you should specify this in the Start of feed configuration dialog.
For further information, please refer to Start of feed.
Many machines require the program to be sent to them as soon as the cycle start button is pressed. Select transmit program at the DNC before pressing cycle start. This requires the PC to start sending when it either sees the handshake line going high (for hardware handshaking) or when it receives an XOn (for software handshaking).
If software handshaking is used then try enabling Wait for XOn in the port transmit settings.
For further information, please refer to Transmit.
Some machines need a specific character to indicate the end of the file. Check the machine manual. Many machines need a % at the end of the file, some need a special control code character like ASCII 0 (NULL), ASCII 3 (ETX) or ASCII 26 (SUB).
If this is the case, you should specify this in the End of feed configuration dialog.
For further information, please refer to End of feed.
Check that your cable is wired correctly.
For information on how to wire a standard serial cable, please refer to Übersicht serielle Kommunikation.
Some machines requires a special non-standard serial cable. For further information, please refer to the reference manual for your CNC.
Remember to verify that the RTS/CTS and DTR/DSR hardware handshake signals are correct.
Try using another serial port, in case you have a defective serial port.
To check that the cable is wired correctly, and that the port is working, you can perform a loopback test.
For further information, please refer to How to perform a loopback test.
See also DNC/CNC reports transmission errors.