HP Plotters - I/O Buffer Overflow (Error 16)
When a print job is sent from the software, the plotter starts to plot then displays "I/O Buffer Overflow" (Error 16). The plotter will either stop completely or start to plot strange characters, lines or exhibit other random behavior.
Several things could cause this problem:
Software is using software handshaking (Xon-Xoff) handshake while the plotter is set to hardware handshake.
The plotter may be connected to a network or a switching device that is not detecting/allowing the proper communication handshake.
The cable may be pinned out incorrectly. The serial I/O on the computer would not be able to detect the change in DTR voltage; consequently, it would continue sending data to the plotter, even though the buffer is overflowing.
SOLUTION: Try the following workarounds:
Set the plotter's serial handshake to Xon-Xoff through the front panel.
Determine whether a direct connection works.
Try decreasing the baud rate on the plotter and in the software so that data is sent at a slower speed. If lowering the baud rate increases the amount of the plot that comes out, the cable is probably failing. Try an HP manufactured cable (9-pin 24542H or 25-pin 17255F). If using a plotter with a parallel interface, try using a parallel connection instead of a serial connection.
If none of the above steps provide the solution, the problem is with the interface port on either the PC or the plotter.
I/O error 16 indicates that the plotter's buffer overflowed. When the buffer was almost full, the plotter signaled the CPU to stop sending data (dropped DTR line voltage on pin 20 for hardware handshake or the plotter sent an Xoff character for software (Xon-Xoff) handshake), but the CPU continued to send data and the buffer overflowed.
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