Omron NT21 - SETUP MANUAL 10-2001 Setup Manual page 32

Connecting Link Adapters
DIP Switch Settings
Pin Allocation
20
Communications Specifications (RS-422A/485 Interface)
Item
Baud rate
Transmission distance
Terminal block configuration
Insulation
Note The RS-422A/RS-485 connector is not insulated from the RS-232C connector.
The NS-AL002 Link Adapter has a 4-pin DIP switch that sets the RS-422A/
RS-485 communication conditions. Set the DIP switch before connecting the
communications cable.
The following table shows the functions of the DIP switch pins. The factory de-
faults are OFF for all 4 pins.
Pin(s) Function
1 Communications mode
2 and 3 Communications method 2-wire (RS-485)
4 Terminating resistance
When using 1:1 NT Link communications, set the communications mode to "No
RS/CS control" by turning OFF pin 1.
When using 1:N NT Link communications (standard or high-speed), set the
communications mode to "RS/CS control" by turning ON pin 1.
The Link Adapter has an RS-232C connector and a terminal block for an
RS-422A/485 interface connection. The pin arrangements for the RS-232C con-
nector and the RS-422A/485 terminal block are as follows.
RS-232C Connector
Pin
1 Not used
2 Receive data
3 Send data
4 Clear to send
(shorted to RS internally)
5 Request to send
(shorted to CS internally)
6 +5 V (30 mA) input for
Link Adapter
7 and 8 Not used
115.2k bps max. (depends on the RS-232C baud
rate)
500 m max.
8-terminal detachable terminal block, M3.0
Non-insulated (See note.)
ON
ON
RS/CS control
Terminator ON
Signal name Code
---
RD
SD
CS
RS
+5 V
---
Section
Specification
OFF
OFF
No RS/CS control
4-wire (RS-232C)
Terminator OFF
Signal direction
(Link Adapter ⇔ NT21)
---
Link Adapter ← NT21
Link Adapter → NT21
Link Adapter ← NT21
Link Adapter → NT21
Link Adapter ← NT21
Pins 7 and 8 are shorted
internally
3-2