115
Expanded System Configuration Section 2-5
Note 1. Set pin 5 of the DIP switch on the front panel of the CPU Unit to OFF, and
set the serial communications mode in the PLC Setup to no-protocol com-
munications.
2. No-protocol communications are supported for Serial Communications
Units with unit version 1.2 or later only.
NT Link System
(1:N Mode)
If the PLC and Programmable Terminal (PT) are connected together using
RS-232C ports, the allocations for the PT’s status control area, status notify
area, objects such as touch switches, indicators, and memory maps can be
allocated in the I/O memory of the PLC. The NT Link System allows the PT to
be controlled by the PLC, and the PT can periodically read data from the sta-
tus control area of the PLC, and perform necessary operations if there are any
changes in the area. The PT can communicate with the PLC by writing data to
the status notify area of the PLC from the PT. The NT Link system allows the
PT status to be controlled and monitored without using PLC ladder programs.
The ratio of PLCs to PTs is 1: n (n
≥ 1).
Set the PT communications settings for a 1:N NT Link. Either one or up to
eight PTs can be connected to each PLC.
Note 1. The PLC can be connected to any PT port that supports 1:N NT Links. It
cannot be connected to the RS-232C ports on the NT30 or NT30C, be-
cause these ports support only 1:1 NT Links.
2. The NT20S, NT600S, NT30, NT30C, NT620S, NT620C, and NT625C can-
not be used if the CPU Unit’s cycle time is 800 ms or longer (even if only
one of these PTs is connected).
3. The Programming Console functionality of a PT (Expansion Function) can
be used only when the PT is connected to the RS-232C or peripheral port
on the CPU Unit. It cannot be used when connected to an RS-232C or RS-
422A/485 port on a Serial Communications Unit.
RS-232C
RS-422A/485
PT
PT PT
RS-232C
1:N Mode
PT
1:N Mode
RS-232C to RS-422/485
Conversion Adapter
Applicable port
Peripheral port
Yes
(See note 1.)
RS-232C
Yes
(See note 2.)
Serial
Communi-
cations
Unit
Yes
CPU Unit
Note 1. Turn ON pin 4 on the DIP switch on
the front of the CPU Unit and set the
serial communications mode in the
PLC Setup for an NT Link.
2. Turn OFF pin 5 on the DIP switch on
the front of the CPU Unit and set the
serial communications mode in the
PLC Setup for an NT Link.
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