• Transmit timing of X-on signal

The X-on signal is transmitted when the power is first turned on, or when the vacant area in the buffer is greater than the specified value (typically 512 bytes; refer to your printer manual).

Figure 3 . X - on/X - off thing

X-ON

X-OFF

 

X-ON

 

POWER ON

Buffer capacity

less

Buffer capacity

greater

 

than specified

value

than specified

value

DTR protocol

Under this system, when the printer is turned on the DTR enters the SPACE state, meaning that data entry is enabled. When the rate of data reception is greater than that of printing, the buffer gradually fills up. Once the vacant area in the buffer drops below the specified value (typically 256 bytes; refer to your printer manual), the DTR sets the status flag to prohibit further data entry. This flag is output through the DTR pin (No. 20) at RS-232D signal levels, and through the TTY-TXD pin (No. 17) at Current Loop Levels.

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