1-5
Section
Functions of the DeviceNet (CompoBus/D) Interface Unit
12
ences described above and differences in the hardware used for communica-
tions.
Item
With Regular Memory Link
With DeviceNet Interface Unit
Communications
with host (method
used to read/write
PT memory)
Data transfer by Memory Link commands via
RS-232C or RS-422A communications
•
Data transfer through the DeviceNet input and
output areas (The contents of corresponding
words in the host are updated automatically.)
•
Data transfer by explicit message communica-
tions
Refer to 1-5-1 Communications Using the
DeviceNet Interface Unit for more details.
Functions possible
between the PT and
host
The following functions can be executed with
the Memory Link command:
•
Read/write PT memory, numeral memory
tables, character string tables, or bit memory
tables.
•
Clear numeral memory tables, character string
tables, or bit memory tables.
•
Notify the host of a touch switch, numeral, or
character input.
•
Notify the host of a change in the direct area or
PT memory.
•
Change the PT’s operating mode.
•
Send a resend request to the PT.
•
Return an error response to an illegal command
from the host.
The following functions can be executed by
sending explicit messages:
•
Read/write PT memory.
(Data is automatically transferred through the
input and output areas. Data can be transferred
to or from any area with explicit message com-
munications.)
Structure of the PT
status notify area
PT status notify bits
0
0
0
Bit
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Word m
Word m+1
Word
Numeral/character string memory table number
(4-digit BCD or hexadecimal)
Bit
Screen number (4 BCD digits)
Numeral/character string memory table number
(4-digit BCD or hexadecimal)
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Word m
Word m+1
Word m+2
Word
0
0
0
PT status notify bits
PT status notify
area’s “Displayed
screen number”
None
(The current screen number can be found in
the PT status control area’s “screen number”.)
Notify the host of the displayed screen number.
Strobe of the PT
status notify area’s
“PT status notify bit”
The strobe goes ON for a fixed time when the
displayed screen is changed or the contents of
the numeral or character string memory table
are changed. (At the same time, the host is
notified by the Memory Link command.)
The strobe goes ON for time set in the system
menu. (There is no notification to the host. The
strobe’s ON time must be longer than the
interval between data reads from the host.)
Window control
area
Normally, this area is used in both directions
and the contents of this area are mirrored in the
corresponding area in the host.
•
Specification of the displayed window from the
host to the PT
•
Notification of the displayed window from the
PT to the host
•
When allocated to the input area, only notifica-
tion of the displayed window from the PT to the
host is performed.
•
When allocated to the output area, only specifi-
cation of the displayed window from the host to
the PT is performed.
•
When allocated to an area other than the input
or output area, it is necessary to regularly read
the contents to recognize changes and write
data to control the displayed window.
Notification to the
host
Notify the host with the notification command.
None. (The user must confirm contents by
regularly reading data at the locations where
changes are expected or allocating part of the
input area so that data is read automatically.)
System program in
the PT
Use the factory-installed system program or the
system program included with the Support Tool.
Install the system program included with the
DeviceNet Interface Unit.
