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Section 6: Using the Printer Interface
102
The following diagram illustrates DTR Protocol Timing.
Legend:
1 The RTS signal is driven directly by the RS-232C line driver and is active
any time power is supplied to the printer.
2 The DTR signal becomes active (high) when initialization is complete,
telling the computer that the printer is ready to receive data.
3 DTR drops (low) to tell the computer that the printer buffer is full or the
printer is busy and data transmission should stop. If the computer con-
tinues to send data after the printer lowers the DTR signal, data could be
lost. DTR is raised (high) when the printer is again ready to receive data.
XON/XOFF Protocol Timing
When you select this flow control protocol, the printer sends an XOFF
command to the host to indicate that the printer cannot receive more data
because it has one of the following conditions:
• Buffer full
• Attendance error (paper out, printer error)
• Printer is not in ready state
The following diagram illustrates XON/XOFF Protocol Timing.
Legend:
1 Data received when DSR is low is invalid and discarded.