6.2.3I/O SIGNALS
(1)RD
Serial receiving data signal. On occurrence of framing error, overrun error, or parity error, the data is printed as "?".
(2) DTR
When this signal is READY, write data or a command. When they are written in BUSY, overrun error is occurred and data is ignored. Even during printing, data can be loaded in the input buffer. Further, BUSY can take place on supply of power, during test printing, during
(3) TD
When, while in data reception, the input buffer on the printer side has only 128 bytes .or less left,DC3 (13H) data reception impossible signals are output. When the input buffer has 256 bytes
left, DC1 (11H) data reception possible signals are output to the host. When DTR/DSR control having been selected in status information transmission, it is first confirmed that DSR is "space" and data is sent. When DTR/DSR control has not been selected, DSR is ignored and data is transmitted.
(4) FG
Case GND
(5) GND
Common GND on the circuit.