Omron NT20, User Manual

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Memory Tables and Bar Graphs Section 5-2
Also, by relating the numeral memory table entries with the bar graphs, the
bar graphs corresponding to the data of the numeral memory table entries
can be displayed.
During the operation, the display contents are automatically updated so that
the contents of the numeral memory table entry being displayed are the same
as that of the PLC word.
There are two methods for referencing numeral memory table entries used for
numeral displays, as follows:
• Direct specification
• Indirect specification
Note The only method available for numeral memory table entries used for graphs
and numeral settings is direct specification.
• Direct Specification
Direct specification is a method of specification in which the contents of
displayed memory table entries are directly correlated with the contents of
the allocated words.
• Indirect Specification
With indirect specification, the contents (numerical value) of the specified
numeral memory table entry are regarded as a memory table entry number
and the contents of the table entry with this number is displayed.
Up to 50 numeral displays and 50 character string displays can be speci-
fied on one screen by using indirect specification.
This specification method is a little complex, but it allows the display to be
changed more easily according to the circumstances. In the example
above, if one were added to the contents of memory table entry 18 to give
63, the contents of memory table entry 63 would be displayed instead.
The memory table entries used for display can also be allocated to areas
in the PLC, so that the display can also be changed in response to changes
in the data to be displayed (i.e., the contents of character string memory
table entry 62 in the example above). However, in comparison with direct
specification, indirect specification requires more time for processing.
Setting the Words of the Numeral Memory Table
When creating the screen data by using the Support Tool, make the following
settings for each numbered numeral:
NT20
PLC
0 0 6 2
Character string
memory table entry 18
0 0 6 2
0 6 0 2
Allocated word
(character string memory
table entry 18)
Direct
specification
DM0100
NT20 PLC
7 7 7 7 0 0 6 2
7 7 7 7
0 6 0 2
7 7 7 7
DM0200
DM0100
Allocated word (character string
table entry 62)
Indirect
specification
Character string
memory table entry 62
Numeral memory
table entry 18
Allocated word
(numeral memory table entry 18)