Nt20S Internal Processing - Omron NT20S Operation Manual

NT20S Internal Processing

When the direct connection function is used, the following processing is executed inside the NT20S. Processing is
divided into two types: periodic processing and event processing.
Periodic Processing (When Using Direct Connection)
The following processing is executed inside the NT20S to enable high-speed control from the PC.
Usually, the only data read from the PC area the elements used for the currently displayed screen. Even if the con-
tents of the PC words allocated to memory tables are changed, these contents are not updated at the PT unless the
memory table is used for the displayed screen.
[NT20S (PT) processing]
PT power ON
Initial processing
Operation start
Initial values written to the memory
tables
Screen switching
Screen element registration
Reading of registered
elements
Reading of elements
that could not be
registered.
Reading of the
elements that could not
be registered.
Reading the PT status
control area
Reading of elements
that could not be
registered
Reading of elements
that could not be
registered
Reading of the PT
status control area
252
APPENDIX E
NT20S Internal Processing
(PT ³ PC)
(PT ³ PC)
(PT ² PC)
(PT ² PC)
(PT ² PC)
(PT ² PC)
(PT ² PC)
(PT ² PC)
(PT ² PC)
[Details of processing]
Hardware check, communication status check, etc., executed.
When the values registered in the NT20S are used as the initial
values in the memory tables, these values are written into the
allocated words of the PC.
In order to enable fast batch processing, the elements used in
the displayed screen are registered in the PC in advance.
Approximately 120 words can be registered per screen.
The statuses of the registered elements are read from the PC
and the display is changed.
The status of the elements that were in excess of the registrable
number and could not be registered is read from the PC, and
the display is changed. This processing is continued until the
statuses of all the remaining elements has been read.
If the number of elements that could not be registered is large,
the PT status control area is read after every two element
readings.
: Processing performed if necessary
Appendix E