Specifications

2-28 Hardware

Confidential

DC characteristics: TTL level

AC characteristics: Minimum reset pulse width TR: 50 µs (min)

NOTE:

The letter ”n” before a signal name indicates an active LOW signal.

Reception of status from the printer through the bidirectional parallel interface

In the bidirectional parallel interface specifications, printer status transmission is available by

using the both-way communication facility in the Nibble/Byte Modes in accordance with IEEE

1284 specifications.

In this case, as opposed to the RS-232C serial interface specifications, the real-time interruptions

from the printer to the host are disabled and thus precautions must be taken to the following:

1. The allowable capacity of the printer internal buffer is 99 bytes (except for ASB status). The

status signals exceeding this capacity will be discarded. To prevent possible loss of status,

the host shall be ready for data acceptance (Reverse Mode).

2. When ASB is used, the host is preferably in the wait state for data acceptance (Reverse Idle

Mode). When this state is not available, the host shall enter the Reverse Mode to constantly

monitor the presence of data.

3. When ASB is used, preference shall be given to the ASB status for transmission over the

other status signals. Any accumulated ASB status signals left for transmission from the last

to the newest ASB status transmission shall be transmitted together at a time as one ASB

status showing the presence of change, followed by the latest ASB status.

Example: In the normal (wait) state, the ASB status is configured as follows:

First Status Second Status Third Status Fourth Status

0001 0000 0000 0000 0110 0000 0000 1111

nSelectIn

(1284-Active)

nInit

min. 0

min. 1 ms

min. 50