Omron NT21 User Manual

2-7SectionTouch Switches
129
Set
When the touch switch is pressed, the notify bit comes ON, and it remains ON
after the switch is released.
Pressed Released Pressed Released
↓↓ ↓↓
Notify bit
0 (OFF)
1 (ON)
Reset
When the touch switch is pressed, the notify bit goes OFF, and it remains OFF
after the switch is released.
Pressed Released Pressed Released
↓↓ ↓↓
Notify bit
0 (OFF)
1 (ON)
Reference: If there the same bit is allocated for more than one momentary touch switch on
one screen, and more than one switch is pressed and released at the same time,
the OFF status will be notified each time one of the switches is released.
Notes on Notification Operations
The manner in which touch switch notification is executed differs according to
the notification operation and communication method as follows:
Type of notifica-
tion operation
 Host link
 NT link for C or CVM1/CV-se-
ries PCs in the DM or EM
Area
 NT link for C or CVM1/CV-se-
ries PCs in an area other than
the DM or EM Area
 NT link for CS/CJ-series PCs
in any area
Momentary Set
Reset
(1) Notification in word units
(all other bits in the word
are OFF)
(3) Notification in bit units
Alternate
(2) Notification in word units
(note that the word
contents are read on
display and notification is
based on these contents)
(4) Notification in bit units
When using touch switch input notification, note the following points.
• In the case of (1) in the table, the other bits in the same word are turned OFF by
notification.
10
0
1
15 14
Bit
Touch switch pressed
Bit
Touch switch
notify bit
Bits other than
notify bit go OFF
01
10
15 14
0
01
0
Bit turned ON by
ladder program
• As shown in the example above, the only bits that are turned OFF are the ones
that were turned ON by processes other than PT operations, such as the lad-
der program or a Programming Device.
In the NT21, NT31/NT31C, and NT631/NT631C, changes to bits by PT pro-
cesses are always reflected correctly so the same word can be allocated for
the momentary, alternate, set, and reset touch switches. (In the earlier NT20S,
NT30/NT30C, and NT620S/NT620C/NT625C PTs, the same word could not
be allocated for the momentary touch switch because the other switches’ op-
erations would turn OFF the momentary touch switch’s ON notification.)
• In the case of (2) in the table, since notification is executed on the basis of the
contents of the word before the display, the other bits in the word are not over-

Omron NT21 Specifications

General

Brand	Omron
Model	NT21
Category	Touch terminals
Language	English