Omron NT20, User Manual

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Communications with PLC by Direct Connection Section 1-4
1-4 Communications with PLC by Direct Connection
1-4-1 Functions of the Allocated Bits and Words
When using an NT20-ST121 @ with the direct connection function (host link or
NT link), the elements displayed on the NT20 and the NT20 status can be
allocated to the bits and words of the PLC. By changing the contents of the
bits and words, the NT20 can be controlled by the PLC. It is also possible to
send data to the PLC by pressing the touch switches on the NT20.
• Controlling the NT20 by a PLC
The following NT20 functions can be controlled by a PLC.
Screens: Display of designated screens, confirmation
of screen numbers, etc.
Memory tables: Writing to a memory table, copying from a
memory table entry to another memory table
entry, etc.
Lamps and touch switches: Display instructions, confirmation of display
status, etc.
System control: Buzzer ON/OFF, backlight ON/OFF, and oth-
er NT20 status
• Notifying the PLC from the NT20
Data in the NT20 is sent to a PLC when a touch switch is pressed. The fol-
lowing types of data are sent to a PLC.
• NT20 status
• Touch switch status
• Numerical values input with touch switches by using the numeral set-
ting function
• Changes in a memory table after copying between memory table en-
tries
Functions of Display Elements
• Lamps
Allocation destination: Bit
PLC’s bit status is displayed by the “Lamp” on the NT20.
The lamp comes on (flashes) when the PLC’s bit status (lamp bit) is ON
(1), and goes off when it is OFF (0).
Lamp #1 (Bit 000100)
Lamp #2 (Bit 000101)
Switch 1: ON (Bit 000100)
Switch 2: OFF (Bit 000101)
NT20 PLC
Lit
Unlit