Each harmonica consists of eight 6-wire 6-position RJ11 jacks connected to one 50-pin male Telco connector. Note that a patch panel simply consists of a set of harmonicas mounted in one panel. USOC is a common way of wiring the RJ11 jacks to the Telco connector, and it is the standard we use at APO. Always buy USOC harmonicas and patch panels for RS-232 distribution!
RJ11 Pin
Signal
Male Telco Connector Pin
Jack #1
Jack #2
Jack #3
Jack #4
Jack #5
Jack #6
Jack #7
Jack #8
1
Tx Flow
28
31
34
37
40
43
46
49
2
Tx
27
30
33
36
39
42
45
48
3
Tx Gnd
4
7
10
13
16
19
22
Rx Gnd
26
29
32
35
38
41
44
47
5
Rx
8
11
14
17
20
23
6
Rx Flow
9
12
15
18
21
24
Note that Telco pins 25 and 50 are not connected
