4–10 Scanner Configuration and Programming
Publication
17476.6 - July 1996
The following sections contain information that you must understand
before you configure your scanner’s G file.
G File Considerations
•
You can only change the RIO configuration by modifying the G
file while offline in your program file. Your application program
cannot access the G-file, nor can you access it while online with
your programming device. However, your SLC control program
can dynamically inhibit and uninhibit RIO devices via the M0
file.
• RIO devices larger than 1 logical rack appear as multiple devices
on the RIO link. Refer to the Crossing Logical Rack Boundaries
section below.
• The address and size of the devices you list in the G file must
match the settings of each RIO device.
Crossing Logical Rack Boundaries
You express remote I/O image boundaries in an even number of
groups. For example, the 1747-ASB image can be any size from two
logical groups up to 32 logical groups (four logical racks), in 2
logical group increments.
If the scanner image assigned to an adapter is greater than 8 logical
groups (one logical rack), the image crosses logical rack boundaries.
If the scanner image assigned to an adapter is less than 8 logical
groups, it too can cross a logical rack boundary depending upon the
starting logical group number. The significance of crossing logical
rack boundaries is discussed in the next section.
Examples of Crossing Logical Rack Boundaries
Examples 1 and 2 that follow show adapters with logical image sizes
that cross logical racks 0 and 1. The image size of the adapter in
example 1 consumes all of logical rack 0 (eight logical groups) and
half of logical rack 1 (four logical groups). The image size of the
adapter in example 2 consumes two groups in logical rack 0 and four
groups in logical rack 1.
Considerations When
Configuring Remote I/O
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