Specifications

Confidential
EPSON
TITLE
SHEET
REVISION
NO.
SHEET NEXT
D
TM-U230
Specification
(STANDARD)
20 21
2.1.2.9 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 bidirectional communication facility in the Nibble/Byte Modes in accordance with the IEEE 1284.
In this case, as opposed to 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 following.
1) Allowable capacity of the printer internal buffer is 99 bytes (except ASB status). 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 one 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 0000 0000 0000 0000
When the following sequence of operations proceed and near end is detected, and
the FEED button is pressed and released, the following pieces of data are
accumulated.
First Status Second Status Third Status Fourth Status
①
0001 0000 0000 0000 0000 0011 0000 0000
Near end detection
②
0101 1000 0000 0000 0000 0011 0000 0000
FEED button is pressed
③
0001 0000 0000 0000 0000 0011 0000 0000
FEED 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)
0101 1000 0000 0000 0000 0011 0000 0000
+
First Status Second Status Third Status Fourth Status
The latest ASB (③)
0001 0000 0000 0000 0000 0011 0000 0000
Fourth Status