Specifications

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6. INTERFACES
6.1 Bidirectional Parallel Interface (IEEE1284)
6.1.1 Specification
1) Compatibility Mode (Host → Printer Communication: Centronics Compliant)
(1) Outline
Compatibility Mode is a standard of Centronics interface that has been used for long.
(2) Specification
Data transfer system: 8 bit parallel
Synchronization: By the nStrobe signal supplied from outside
Handshake: By the nAck signal and Busy signal
Signal level: All signals are TTL compatible.
2) Reverse Mode (Printer → Host Communication)
Transfer of status data from this printer to the host is made in the Nibble or Byte Mode.
(1) Outline
This mode specifies the data transfer from the asynchronous printer controlled by the
host.
Data transfer in the Nibble Mode is carried out through existing control line and data is
transferred in steps of 4 bits (Nibble).
In the Byte Mode, data is transferred through the 8-bit data line treated for bidirectional
transmission.
In any case, as concurrent execution with Compatibility Mode is not available,
communication is made in half duplex mode.
When using this mode, use CN1-38 and 39 pins in addition to the parallel interface
terminal of the interface cable.
CN1-38 pin: nAUTOFD
CN1-39 pin: nSELECTIN
Unless these two pins are used, bidirectional communication cannot be implemented. If
you don’t want to use bidirectional communication, set the terminal to be Non Connect.
* The first “n” of a signal name indicates “LOW” active signal. If any one of the above
signals is missing, bidirectional communication is impossible. Always use twisted pair line
for signal lines of interface while connecting the return side to the signal ground level. All
the interface conditions shall be based on C-MOS level and satisfy the following
characteristics. Rising and falling time of each signal shall be 0.5 µs. Never carry out
data transfer by ignoring the nAck signal or Busy signal. Otherwise, data transfer may
result in loss of data. Interface cable shall be minimum necessary length.