Epson EMP-TW 1000, Справочное руководство

Страница: 176 / 268

vi When the unit attention condition is set, the Target sends Check
Condition status and then advances to item ix without
executing the command.
vii The Target rechecks the command operation code. If the
command is Test Unit Ready, the command is executed. If
there is a parameter error, however, the Target creates an
error code and sense data and then advances to item ix. If the
command operation code is not Send or Receive, the
command is not supported by the scanner; the Target creates
sense data and then advances to item ix.
viii If the Target receives the Identify message in item ii, it checks
the Disconnect bit of the message, sends the Disconnect
message if necessary, and changes to the Bus Free Phase.
After completing preparations for data send and receive, the
Target checks to determine if the Bus Free Phase is in effect,
performs Arbitration and Reselection, reconnects to the
Initiator, changes to the Message In Phase, and sends the
Identify message.
The Target checks the operation code of the command
received in item iv. If there is no error in the parameters, the
Target executes the Send and Receive commands. If there is
a parameter error, however, the Target creates an error code
and sense data.
ix The Target changes to the Status Phase and checks for error
codes. If an error is present, the Target sends Check
Condition status; if there is no error, the Target sends Good
status.
x The Target changes to the Message In Phase and sends the
Command Complete message; it then changes to the Bus
Free Phase to complete the series of communications.
A-14
Interface Specifications