1747-6.22, Backup Scanner User Manual

7-108 RIO Block Transfer
Example 1
1747-SN RIO Scanner’s I/O Image Files
Logical
Rack 0
Logical
Rack 3
Group 0
Group 1
Group 2
Group 3
Group 4
Group 5
Group 6
Group 7
Group 0
Group 1
Group 7
Group 0
Group 1
Group 2
Group 3
Group 4
Group 5
Group 6
Group 7
Publication 1747-6.22
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Input Image Output Image
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
Logical Slot 0
Logical Slot 1
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.
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.
Note that the logical address of you
RIO devices (i.e., adapter and
intelligent I/O modules) determine
where the block transfer gets mapped.