GE GFK0579B 用户手册
3
Remote I/O Scanner User’s Manual – July 1992
50
Using Option Modules in a Remote Drop
PCMs (Programmable Coprocessor Modules), GDS (Graphics Display Coprocessor
Modules), and ADS (Alphanumeric Display Coprocessor Modules) can be located in a
remote drop.
Modules), and ADS (Alphanumeric Display Coprocessor Modules) can be located in a
remote drop.
These option modules look at the Remote I/O Scanner as though it were a Series
90–70 PLC CPU. They can read and write to any locations in the Remote I/O Scanner’s
internal %I, %AI, %Q, %AQ, and %R memories, including those portions of memory
that are outside the range configured for data transfer with the system host.
90–70 PLC CPU. They can read and write to any locations in the Remote I/O Scanner’s
internal %I, %AI, %Q, %AQ, and %R memories, including those portions of memory
that are outside the range configured for data transfer with the system host.
The Remote I/O Scanner’s %R memory is NOT used for data transferred with the
CPU, but it can be freely accessed by a PCM, GDS, or ADS module in the remote drop.
CPU, but it can be freely accessed by a PCM, GDS, or ADS module in the remote drop.
Accessing the Host CPU from Option Modules in a Remote Drop
When used in a remote drop, a PCM, GDS, or ADS module does not have direct access
to host CPU memory; to read or write host memory, the data must be transferred
through the configured memory area of the Remote I/O Scanner. The area used
should not correspond to a physical I/O module; it should correspond to an unused
portion of the remote drop I/O map configured for the remote drop.
to host CPU memory; to read or write host memory, the data must be transferred
through the configured memory area of the Remote I/O Scanner. The area used
should not correspond to a physical I/O module; it should correspond to an unused
portion of the remote drop I/O map configured for the remote drop.
Extending the I/O map of a remote drop will cause the Genius message to increase in
size, and will therefore increase the Genius bus scan time. Gaps may be anywhere in
the I/O map, but if they are added to the end, the corresponding I/O references cannot
be used for any other purpose by either the host or the Remote I/O Scanner.
size, and will therefore increase the Genius bus scan time. Gaps may be anywhere in
the I/O map, but if they are added to the end, the corresponding I/O references cannot
be used for any other purpose by either the host or the Remote I/O Scanner.
Reading Host Data from an Option Module
% Q
% AQ
a44887
PCM, GDS
OR ADS
HOST
CPU
REMOTE I/O
SCANNER
MEMORIES
READ
MEMORIES
OUTPUT
MODULES
GENIUS
MESSAGE
% Q
% AQ