9
REV. 2.0.1
SP338/SP339/XR34350 EVALUATION BOARD USER’S MANUAL
2.1.7
Half-Duplex RS-485 Mode #2 (SP338 Only)
Figure 8
below shows the SP338/339/XR34350 configured in the half-duplex RS-485/422 mode #2.
?
J23 Pins 7 & 8 (MODE0) - ’0’
?
J23 Pins 9 & 10 (MODE1) - ’1’ (jumper installed between these pins)
?
J23 Pins 11 & 12 (MODE2) - ’1’ (jumper installed between these pins)
The RS-485 signals are also accessible at J16.
F
IGURE
8. H
ALF
-D
UPLEX
RS-485 M
ODE
#2
R2
R3
R4
R6
R7
R8
R9
TP6
TP8
TP26, TP51
TP22, TP42
TP20, TP41
Sl
ew
Di
r1
Mo
de
0 =
0
Mo
de
1 =
1
Mo
de
2 =
1
Ter
m
InvDi
r
En
abl
e =
1
Vc
c
R1
T1
R4
120O
11
12
13
14
15
16
17
18
19
20
40
39
38
37
36
35
34
33
32
31
1
2
3
4
5
6
7
8
9
10
30
29
28
27
26
25
24
23
22
21
All pull-downs 330kO
R1
V+
C2+
Vc
c
C1+
C1-
C2-
V-
Vc
c
C3
0.1
µF
C2
0.1
µF
C1
0.1
µF
C4
0.1
µF
Cc
1.0
µF
L1 = 1
L2
L3
L6 = 1
L8 = 1
L9 = 1
Vcc
