APPENDIX
buffer is below 256 bytes. After the host computer detects that the DTR signal line is at “MARK”, transmission of the data text is stopped. In this instance, data can still be received up until the data buffer becomes completely full.
When the empty space in the data buffer is increased by following printing (when the data in the data buffer is reduced to 256 bytes or less), the printer sets the DTR signal line to “SPACE”.
Data buffer
Full | Near Full | Near Empty | Empty | |||
Empty area |
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| Reception data | ||
256 bytes |
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| 256 bytes | ||
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DTR"MARK" |
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| DTR"SPACE" |
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[Paper out]
When the “paper out” detector senses the end of the paper, the printer stops printing after printing or feeding a maximum of two more lines on the paper. Immediately after a “paper out” condition is detected, the printer sets to OFF LINE and the DTR changes to “MARK”. (To reset printer after a “paper out”, load paper into the printer and press the ON LINE switch to set the printer to ON LINE.)
[Mechanical error]
Mechanical errors are detected when the motor locks and the unit will not print. Immediately after a mechanical error occurs, the printer sets the DTR to “MARK” and then sets the printer to OFF LINE. To cancel a mechanical error, turn the power to the printer off and remove the cause of the error then turn the power on again to reset the printer.
[Framing error]
A framing error occurs when “SPACE” is detected at the stop bit. When a framing error or a vertical parity error occurs for the data which is received, the printer prints out a “?” mark to indicate that the error occurred.
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