12-32
Installation
BE1-951
D 2 8 4 8 - 0 5
03-18-99
2 2
6
4
A
B
C
T O B E 1 - 9 5 1
3 P O S I T I O N
T E R M I N A L B L O C K
D B - 3 7 F E M A L E
T O R S 4 2 2 / R S 4 8 5
1 9
2 4
C
B
A
A
B
C
4000'
M A X .
C O M 2
B E 1 - 9 5 1
B E 1 - 9 5 1
C O M 2
B E 1 - 9 5 1
C O M 2
R
t
t
R
R = O P T I O N A L T E R M I N A T I N G
t
R E S I S T O R ( 1 2 0
$
T Y P I C A L )
A5
D 5
D 4
D 3
D 5
D 4
D 3
D 5
D 4
D 3
Figure 12-36. SEL 2020 to BE1-951 Relay
RS-485 connections are made at a three-position terminal block connector that mates with a standard
communication cable. A twisted pair cable is recommended. Connector pin numbers, functions, names,
and signal directions are shown in Table 12-2. An RS-485 connection diagram is provided in Figure 12-34.
Table 12-2. RS-485 Pinouts (COM2)
Terminal
Function
Name
Direction
A3 (A)
Send/Receive A
SDA/RDA
In/Out
A4 (B)
Send/Receive B
SDB/RDB
In/Out
A5 (C)
Signal Ground
GND
N/A
Figure 12-37. RS-485 DB-37 to BE1-951
