5–6 RIO Block Transfer
Publication
17476.6 - July 1996
Scanner I/O Image Allocation For Block Transfer
Block transfer operations (BTR and BTW) consume only one byte of
the RIO scanner’s I/O image file, independent of what type of I/O
slot addressing is used. This one byte image is reserved for
communication “handshake” purposes between the remote device
(adapter or intelligent I/O module) and the scanner. SLC control
programs must never read/write to these image locations because
unpredictable operations may result.
Block transfer operations (BTR and BTW) can be addressed to any
logical slot within the RIO scanner’s four logical racks. See the
examples below and on the following page.
Examples of BT I/O Image File Allocation
Word
8
Word 9
Word 7
Word 5
Word 6
Word 3
Word 4
Word 1
Word 2
Word 0
Logical
Rack 0
Word 26
Word 27
Word 25
Word 30
Word 28
Word 29
Word 31
Logical
Rack 3
Input Image Output Image
The minimum portion of the scanner's
image that can be assigned to an adapter
is 1/4 logical rack. Each logical device
that you assign BT operations (BTR or
BTW) consumes one byte from the
scanner's input and output image file.
The one byte can come from either the
low" byte (Logical Slot 0) or the high"
byte (Logical Slot 1). Logical Slot 1 only
applies for 2 slot addressing.
Group
0
Group 1
Group 2
Group 3
Group 4
Group 5
Group 6
Group 7
Group 0
Group 1
Word 24
Word 23
Group 0
Group 1
Group 2
Group 3
Group 4
Group 5
Group 6
Group 7
Group 7
Logical Slot 0
Logical Slot 1
Note that the logical address of your RIO
devices (i.e., adapter and intelligent I/O
modules) determine where the block
transfer gets mapped.
1747SN RIO Scanner's I/O Image Files
In this example there are two block transfer
operations mapped to the scanner' s I/O
image. One BT operation is mapped to
Logical Rack 0, Logical Group 4, Logical
Slot 1. The other is mapped to Logical
Rack 3, Logical Group 4, Logical Slot 0.
Example
1
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