Allen-Bradley 1747-SN User Manual page 181

G–2 Glossary
Publication 1747 6.6 - July 1996
Inhibit A function by which the scanner stops communicating
with a logical device. The logical device will consider itself
inhibited if it does not receive communications from the scanner
within a certain period of time.
Input file The scanner's input image file that is updated during
the SLC processor input scan.
Local Expansion Chassis
SLC chassis using a 1747-C9 (91.4 cm [36 in.]) or 1747-C7 (15.2 cm
[6 in.]) cable.
Local SLC Chassis
and scanner.
Logical Device Any portion of a logical rack that is assigned to a
single adapter. Adapters may appear as more than one logical
device.
Logical Group A logical group consists of one input and one
output word within a logical rack. A word consists of 16 bits, each
bit represents one terminal on a discrete I/O module.
Logical Rack A fixed section of the scanner image comprised of
eight input image words and eight output image words.
Logical Slot A logical slot consists of one input and one output
byte within a logical group. A byte consists of 8 bits, each bit
represents one terminal on a discrete I/O module.
M files The SLC M0 and M1 data files that reside in the scanner.
M files contain RIO network status (M1) and control (M0)
information. The contents of these files can be directly accessed by
your application program. Also, the M files are used to control and
monitor RIO block transfer operations.
Output file The scanner's output file that is updated during the
SLC processor output scan.
Remote Chassis The chassis containing an ASB module and
connected to the local SLC chassis via the RIO link.
Remote Expansion Chassis
remote chassis using a 1747-C9 (91.4 cm [36 in.]) or 1747-C7 (15.2
cm [6 in.]) cable.
Reset, Adapter Decide
logical device during an RIO discrete transfer. These commands
instruct the logical device to reset all of its discrete outputs if hold
last state is not selected, or to hold all of its discrete outputs in their
last state if hold last state is selected.
A chassis that is connected to a local
The chassis that contains the SLC processor
A chassis that is connected to a
Commands sent by the scanner to a