Omron NT620S Operation Manual page 255

Operation of the Memory Link
6-1 Operation of the Memory Link
6-1-1 What is the Memory Link?
6-1-2 PT Memory
244
This section describes the function of the memory link.
The memory link is a new communication method which allows use of the direct
connection function from a host with RS-232C or RS-422A communications.
In ordinary direct connection, each of the display elements of the NT620S/
NT620C is allocated to the PC memory of the host. In contrast, when using the
memory link, the NT620S/NT620C has an area in its memory called the "PT
memory" and direct connection is executed with respect to this area, treating it as
though it were a memory area in a PC.
By issuing memory link commands when necessary, the host can read and write
the contents of the PT memory and the contents of NT620S/NT620C memory
tables. Also, when touch switches are pressed or numeric values or character
strings are input at the NT620S/NT620C side, the NT620S/NT620C issues a
command to notify this input to the host.
PT
PT memory
Numeric value displays
0000
Character displays
Lamps
Graphs
Touch switches
Numeric value input
9999
Character input
Therefore "memory link" is virtual direct connection executed at the NT620S/
NT620C and controlled by commands from the host.Memory link has the follow-
ing restrictions when compared with host link and NT link.
S The only area that can be used for allocation is the I/O relay area (word area).
The PT memory is a virtual PC area within the NT620S/NT620C. However, there
is no classification of the area as there is with real PC areas: it consists of an I/O
relay area of just 10000 words from 0000 to 9999. Consequently, only I/O relay
words can be designated as allocated words.
Memory link can be treated in exactly the same way as direct connection, except
RS-232C communication
RS-422A communication
Memory R/W commands
Table operation commands
Input notification
commands
Section 6-1
Host