Epson TM-U950P Specifications - Page 41

Reception of status from the printer through the bidirectional parallel interface

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2.1.4 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 100 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, the ASB status is configured as follows. First Status 0001 0000 Second Status 0000 0000 Third Status 0000 0000 Fourth Status 0000 0000 When a sequence of operations are proceeded, near end detection cover open the following pieces of data are accumulated. cover closed, First Status Second Status Third Status Fourth Status À 0001 0000 0000 0000 0000 0011 0000 0000 Near end detection Á 0011 1000 0000 0000 0000 0011 0000 0000 Cover open  0001 0000 0000 0000 0000 0011 0000 0000 Cover closed When the ASB status is received following this, a total of eight (8) bytes of ASB will be transmitted as follows. Accumulated ASB (À+Á+Â) First Status Second Status Third Status Fourth Status Accumulated ASB (À+Á+Â) 0001 0000 0000 0000 0000 0000 0000 0000 + The latest ASB (Â) Fourth Status First Status 0001 0000 Second Status 0000 0000 Third Status 0000 0011 Fourth Status 0000 0000 TITLE EPSON TM-U950/U950P Specification (STANDARD) SHEET NO. REVISION AF NEXT 2158 SHEET 1274-5

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EPSON
TITLE
SHEET
REVISION
NO.
SHEET
NEXT
TM-U950/U950P
Specification
(STANDARD)
2.1.4
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 100 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, the ASB status is configured as follows.
First Status
Second
Status
Third Status
Fourth Status
0001 0000
0000 0000
0000 0000
0000 0000
When a sequence of operations are proceeded, near end detection cover open
cover closed,
the following pieces of data are accumulated.
First Status
Second
Status
Third Status
Fourth Status
°
0001 0000
0000 0000
0000 0011
0000 0000
Near end detection
`
0011 1000
0000 0000
0000 0011
0000 0000
Cover open
´
0001 0000
0000 0000
0000 0011
0000 0000
Cover closed
When the ASB status is received following this, a total of eight (8) bytes of ASB will be transmitted
as follows.
Accumulated ASB (
°
+
`
+
´
)
First Status
Second
Status
Third Status
Fourth Status
Accumulated ASB (
°
+
`
+
´
)
0001 0000
0000 0000
0000 0000
0000 0000
+
First Status
Second
Status
Third Status
Fourth Status
The latest ASB (
´
)
0001 0000
0000 0000
0000 0011
0000 0000
Fourth Status
F
17-5
18