Unit Attention Condition - Epson ES-1000C Reference Manual

4. Send, Receive
Data is sent to and received from the scanner. With this
command, the transfer length and assigned length must be the
same as the actual number of data bytes. For example, when
the ESC G (Start reading) command is to be sent to the
scanner, the transfer length must be 2 bytes; otherwise, an
error occurs and the command is not executed. If the assigned
length is 0, the command is ended.

Unit Attention Condition

When the power is turned on, or a reset is performed with the
RESET condition or Bus Device Reset message, the scanner
enters the Unit Attention condition. The Unit Attention condition
then continues until a command other than Request Sense or
Inquiry is received from the Initiator.
If a command other than Request Sense or Inquiry is received
from an Initiator with a pending Unit Attention condition, the
scanner sends the Check Condition status without executing the
command. If the Request Sense command is received while in the
Unit Attention condition, the scanner sends the Unit Attention
sense data and clears the Unit Attention condition.
A-16
Interface Specifications