SERIAL
4-5. Data Protocol
4-5-1. DTR mode
This mode is accessed when the DIP switch
RXD
DTR
Printing
Data
Buffer full
Data
Buffer empty
Data
Power ON
Immediately after power on (provided that no error occurs), the printer sets DTR to “SPACE” to indicate that it is ready to receive data. When the host detects that DTR is in “SPACE” condition, it begins sending text data over the RXD line.
When the printer’s remaining buffer space falls to *256 bytes or less, the printer sets DTR to “MARK.” The host responds by halting the data transfer. However, note that the printer remains capable of receiving data until the buffer becomes full.
Available buffer space increases as the printer prints the buffered data. When the printer has cleared all but the last *256 bytes of data, it sets DTR back to “SPACE” to indicate that it is ready to receive more data.
Data buffer full Nearly full | Nearly empty | Empty | |||||
*256 bytes |
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remaining |
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DTR |
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“MARK” |
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* 16 bytes when the buffer size is set to 45 bytes
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