Specifications

Confidential
SHEET
21
NO.
SHEET
REVISION
H
TITLE
NEXT
22
TM-U590 series
Specification
(STANDARD)
2.1.2.7 Reception of status from the printer through the bidirectional parallel interface
In the bidirectional parallel interface specifications, the printer status transmission is available by
using the both-way communication facility in the Nibble/Byte Modes in accordance with the IEEE
1284.
In this case, different from in the RS-232 serial interface specifications, the real-time interruptions
from the printer to the host are disabled and thus precautions must be taken to the followings.
1) Allowable capacity of the printer internal buffer is 99 bytes (except ASB status). The status
signals exceeding this capacity will be discarded. To prevent possible loss of status, the host
shall be ready for data acception (Reverse Mode).
2) When ASB is used, the host is preferably in the wait state for data acception (Reverse Idle
Mode). When this state is not available, the host shall enter the Reverse Mode to always
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 (when the TOF/BOF sensor detects that the paper
is present), the ASB status is configured as follows.
First Status Second Status Third Status Fourth Status
0000 1000 0000 0000 0000 0000 0000 0000
When a sequence of operations are proceeded, the FORWARD/REVERSE
button is pressed and released, the following pieces of data are
accumulated.
First Status Second Status Third Status Fourth Status
➀
0000 1000 0000 0000 0000 0011 0000 0000
Near end detection
0010 1000 0000 0000 0000 0011 0000 0000
➁
FORWARD/REVERSE
button is pressed
0000 1000 0000 0000 0000 0011 0000 0000
➂
FORWARD/REVERSE
button is released
When the ASB status is received following this, a total of eight (8) bytes of
ASB will be transmitted as follows.
Accumulated ASB (①+②+③)
First Status Second Status Third Status Fourth Status
Accumulated ASB (①+②+③)
0010 1000 0000 0000 0000 0011 0000 0000
+
First Status Second Status Third Status Fourth Status
The latest ASB (③)
0010 1000 0000 0000 0000 0011 0000 0000
Fourth Status