Applications, Wire termination 4-wire termination – Westermo EDW-100 User Manual
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Applications
=Termination
EDW-100
Slave unit
Slave unit
Slave unit
EDW-100
Slave unit
Slave unit
Slave unit
Max 0.3 metre
=Termination
T+
T–
T+
T-
T+
T-
A
B
R+
R–
T+
T–
R– R+
R+
T–
T–
B’ A’ B A
T+
T+ R–
2-wire termination
4-wire termination
Termination recommendations
The RS-422/485 line must be terminated regardless of the cable length. The termination
is ideally placed at the extreme ends of the cable see examples above. The description
of the RS-422/485 pin outs will vary between manufactures. For some brands the T+
corresponds to A T- to B, R+ to A´ and R- to B´, but other brands might use some other
naming convention. If a unit does not work it can help to swap A and B. If difficulty is
being experience contact Westermo for further guidance.
RS-422/485 general advice
Power
SDRAM
8 MB
FLASH
2 MB
DIP-switch
JTAG
PROCESSOR
DEBUG
Data
Address
CTRL
MAC
XTAL
PHY
XTAL
CLK
RESET
5 V = >3.3
V
3.3 V = >1.5
V
Power
A
Power
B
Connector
I/O
I/O
RJ-45
LED
stretch
D-sub
SERIAL CH 1
Ethernet
1
Po
w
er secondar
y 5
V
RS-232
Screw terminal
RS-422/485
Isolation from all other interfaces
Buffer size
Transmit Buffer 8Kbyte.
Receive Buffer 8Kbyte.