![background image](http://html.mh-extra.com/html/omron/nt21/nt21_setup-manual_744541108.webp)
5-2
Section
Connecting to the Host’s RS-232C Port
97
Connecting the NT21-side Link Adapters to the Host-side Link Adapter (RS-485)
NT21
Host
NT-AL001
RS-485
(Total length
500 m max.)
Link Adapters
(NT-AL001 or
NS-AL002)
NS-AL002
NT-AL001
Pin number
Abbreviation
F. Ground
SG
SDB
SDA
RDB
RDA
CSB
CSA
DIP Switch Settings
NT-AL001:
Pins 1, 3, 4, and 6 ON
Pins 2 and 5 OFF
NS-AL002:
Pins 1 to 3 ON
Pin 4 OFF
NT-AL001 or NS-AL002 Link
Adapter (NT21)
RS-422A
terminal
block
NT-AL001
1
2
3
4
5
6
7
8
NS-AL002
1
---
3
7
2
6
---
---
Pin number
1
2
3
4
5
6
7
8
Abbreviation
F. Ground
SG
SDB
SDA
RDB
RDA
CSB
CSA
DIP Switch Settings
Pins 1 to 4 and 6 ON
Pin 5 OFF
RS-422A
terminal
block
NT-AL001 Link Adapter
(Host)
To next PT
Shield
7
5
3
1
8
6
4
2
To avoid an FG ground loop, do not connect the functional ground of the Link
Adapter at the NT21 to the RS-485 cable shielding.
Connecting between the NT21-side Link Adapters (RS-422A)
NT21
Host
NT-AL001
RS-422A
(Total length
500 m max.)
Link Adapters
(NT-AL001 or
NS-AL002)
Pin number
Abbreviation
F. Ground
SG
SDB
SDA
RDB
RDA
CSB
CSA
DIP Switch Settings
NT-AL001:
Pins 1 and 6 ON
Pins 2 to 5 OFF
(Turn ON pin 2 to enable the
terminator in the last Unit.)
NS-AL002:
Pin 1 ON
Pins 2 to 4 OFF
(Turn ON pin 4 to enable the
terminator in the last Unit.)
Link Adapter
RS-422A
terminal
block
NT-AL001
1
2
3
4
5
6
7
8
NS-AL002
1
---
3
7
2
6
---
---
NS-AL002
NT-AL001
Pin number
Abbreviation
F. Ground
SG
SDB
SDA
RDB
RDA
CSB
CSA
DIP Switch Settings
NT-AL001:
Pins 1 and 6 ON
Pins 2 to 5 OFF
(Turn ON pin 2 to enable the
terminator in the last Unit.)
NS-AL002:
Pin 1 ON
Pins 2 to 4 OFF
(Turn ON pin 4 to enable the
terminator in the last Unit.)
Link Adapter
RS-422A
terminal
block
NT-AL001
1
2
3
4
5
6
7
8
NS-AL002
1
---
3
7
2
6
---
---
Shield
NS-AL002
NT-AL001
7
5
3
1
8
6
4
2
7
5
3
1
8
6
4
2