1747-6.22, Backup Scanner User Manual

Local I/O
Remote I/O
Processor I/O Image
Overview 1-19
The SLC processor transfers the scanner’s 4 logical racks (32 input
image and 32 output image words) of discrete remote I/O image data
into the SLC input and output image files. You can adjust the size of
the scanner input and output image file during configuration of your
SLC system so that the scanner only transfers the discrete I/O data
your application program requires. Configuration is done through the
configuration file (G file). Refer to chapter 4, Configuration and
Programming, for more information.
Important: The SLC 500 processor (SLC 5/02 or later) supports
multiple scanners in its local I/O chassis. The maximum
number is dependent on the following:
• backplane power requirements (power supply dependent)
• SLC 500 processor I/O data table limit (4,096 I/O)
Based on SLC processor I/O capacity only, a maximum of eight
scanners may be used when no local I/O exists.
• processor memory to support the application (SLC 500
processor dependent)
Scanner I/O Image Division
The scanner allows each adapter to use a fixed amount (user-defined)
of the scanner’s input and output image. Part of the SLC processor’s
image is used by local I/O; the other portion is used by the scanner for
remote I/O.
The scanner remote I/O image is divided into logical racks and
further divided into logical groups. A full logical rack consists of
eight input and eight output image words. A logical group consists of
one input and one output word in a logical rack. Each logical group is
assigned a number from 0-7.
Logical Rack 0
Logical Rack 1
Logical Rack 2
Logical Group 0
Logical Group 7
Scanner I/O Image
Adapter
Image
The scanner image contains the image of each adapter on the RIO
link. The adapter is assigned a portion of the scanner image, which is
referred to as the adapter image.
Publication 1747-6.22