S
E
RIE
S
IO
S
-52
1 I
/O
S
E
RV
E
R MO
DULE
E
IA
/T
IA
-42
2B
S
E
RIA
L CO
MM
UNICAT
IO
N MO
DULE
_______________
___________________________________________________________________________
- 21
-
9
6
3
E
B
1
1
7
4
1
8
5
6
7
4
2
3
1
F
1
1
5
8
2
A
T
E
R
M
I
N
A
T
I
O
N
+
5
V
A
N
D
G
N
D
B
I
A
S
H
R27
R25
R28
1
C
C
B
SIP
R26
1
P2
D
G
D
A
R23
R24
R28:G
R28:H
R28:D
R28:E
R28:F
R28:A
R28:B
R28:C
R27:F
R27:G
R27:H
DETAIL "A"
R27:C
R27:D
R27:E
R26:D
R27:A
R27:B
R26:A
R26:B
R26:C
R23, 24, 25, & 26
R25:B
R25:C
R25:D
R25:A
R24:D
R24:C
R23:D
R24:A
R24:B
R23:A
R23:B
R23:C
560 O HM
560 O HM
PO RT D
PO RT E
Tx D-D- BIAS G ND
Tx D-E- BIAS G ND
560 O HM
560 O HM
560 O HM
PO RT G
PO RT C
PO RT H
Tx D-C- BIAS G ND
Tx D-G - BIAS G ND
Tx D-H- BIAS G ND
560 O HM
560 O HM
560 O HM
PO RT A
PO RT F
PO RT B
Tx D-A- BIAS G ND
Tx D-F- BIAS G ND
Tx D-B- BIAS G ND
560 O HM
560 O HM
560 O HM
PO RT D
PO RT H
PO RT E
Tx D-H+ BIAS +5V
Tx D-D+ BIAS +5V
Tx D-E+ BIAS +5V
560 O HM
560 O HM
560 O HM
PO RT B
PO RT C
PO RT G
Tx D-B+ BIAS +5V
Tx D-C+ BIAS +5V
Tx D-G + BIAS +5V
120 O HM
560 O HM
560 O HM
PO RT G
PO RT A
PO RT F
Tx D-A+ BIAS +5V
Rx D-G TERMINATIO N
Tx D-F+ BIAS +5V
120 O HM
120 O HM
120 O HM
PO RT F
PO RT F
PO RT G
Tx D-F TERMINATIO N
Rx D-F TERMINATIO N
Tx D-G TERMINATIO N
120 O HM
120 O HM
120 O HM
PO RT H
PO RT C
PO RT C
Rx D-H TERMINATIO N
Tx D-C TERMINATIO N
Rx D-C TERMINATIO N
120 O HM
120 O HM
120 O HM
PO RT E
Tx D-E TERMINATIO N
PO RT H
PO RT E
Rx D-E TERMINATIO N
Tx D-H TERMINATIO N
120 O HM
120 O HM
120 O HM
PO RT B
Rx D-B TERMINATIO N
Tx D-D TERMINATIO N
PO RT D
PO RT D
Rx D-D TERMINATIO N
120 O HM
120 O HM
120 O HM
PO RT A
PO RT A
PO RT B
Tx D-A TERMINATIO N
Rx D-A TERMINATIO N
Tx D-B TERMINATIO N
VALUE
FUNCTIO N
PO RT
P1
R27, R28
IOS-521 PARTIAL VIEW
PIN 1 PO SITIO N IS IDENTIFIED BY A DO T.
FOR REMOVAL AND REPLACEMENT WHERE REQUIRED
RESISTO R IDENTIFICATIO N
RESISTO R SIPS ARE
DIVIDED AS SHO WN
RESISTO R SIPS ARE MO UNTED
IN SO CKETS AND CAN BE
REMO VED IF REQ UIRED.
IOS-521 TERMINATION AND BIAS SIP RESISTOR LOCATION DRAWING
3. THE TxD A ND RTS LI NE S S OURCE D FROM A P ORT CA N B E E NA B LE D V I A
S OFTWA RE . I F S O, THE NE TWORK B I A S RE S I S TORS A S S OCI A TE D WI TH
E A CH P A I R OF S I GNA L WI RE S WI LL NOT B E NE E DE D. THE S E RE S I S TORS
A RE I NS TA LLE D I N S OCK E TS A ND CA N B E RE MOV E D I F THE S E DRI V E RS A RE
A LWA Y S E NA B LE D.
NOTES CONCERNING RESISTOR PLACEMENT AND REMOVAL:
1. A LL TRA NS MI TTI NG A ND RE CE I V I NG CHA NNE LS MA Y HA V E TE RMI NA TI NG
RE S I S TORS (RT) A T B OTH E NDS OF THE NE TWORK . THE I OS -521 HA S US E R-
RE MOV E A B LE P LUG-I N S I P TE RMI NA TI ON RE S I S TORS (120 OHM).
MO DULE IS SHIPPED WITH ALL
SIP RESISTO RS INSTALLED
2. THE RE MUS T B E A T MOS T, ONE S E T OF B I A S RE S I S TORS A S S OCI A TE D
WI TH E A CH P A I R OF S I GNA L WI RE S TO K E E P THE NE TWORK FROM
FLOA TI NG WHE N NO UNI TS A RE TRA NS MI TTI NG.
