Kodak 9500 manual Read command, Command op code 28H Scsi Specification Section, Read data

Read command

Command op code: 28H

SCSI Specification: Section 14.2.5

Command block descriptor

Bit	7	6	5		4	3	2	1	0
Byte
0				Operation Code (28H)
1	Logical Unit Number					Reserved			RelAdr
2					Transfer Data Type
3						Reserved
4	(MSB)				Transfer Identification
5									(LSB)
6	(MSB)				Transfer Length
7
8									(LSB)
9	Vendor Unique				Reserved			Flag	Link

Read data

Descriptor	Data	Definition
Logical Unit	= 0	Only one logical unit
Number
RelAdr	= 0	Not supported
Transfer Type	= 00	Image Data (raster data)
	= 80	Scanner-unique command
	= 81	Header
	= 82	Compound Image (header, raster)
Transfer ID	= 0	Not used when Transfer Type is 00, 81, or 82
	= Scanner Unique	When Transfer Type is 80, this field is used for
		a scanner-unique command.
Command	= length	Maximum number of blocks (block size = 1
Transfer Length		byte) to transfer.
		NOTE: If Transfer Type = 80, use 128*

If the quantity of data is less than the transfer length blocks, Check Condition Status is returned. Incorrect Length Indicator (ILI) will be returned to the Request Sense that follows.

When performing continuous read commands, if a Check Condition returns an indication the buffer is empty (sense key = B, sense code = 80, and sense qualifier = 02), delay subsequent read commands by at least 100 milliseconds.

*For scanner-unique commands, a transfer length of 128 is recommended. The command string is filled with nulls to a length of 128, ensuring the host receives the data without generating a Check Condition for incorrect length.

A-61124 March 1999 5-19