Hardware Reference Manual
421 Intelligent Serial, 8-Port
4.1 I/O Signal Pin-outs
Each serial port has four control signals:
•
TX - Transmitted Data
•
RX - Received Data
•
CTS - Clear To Send (Receive FIFO not full)
•
RTS - Ready To Send (TX FIFO not empty)
To support differential signaling standards (e.g., RS422), each signal has a positive and negative line. When
using a single ended standard (e.g., RS232), use the negative version. All I/O signals are available both at the
front panel connector and on the J4 “backplane” connector. The following table details all connections:
Front Panel Pin
J4 Pin
Port Signal
Positive
Negative
Positive
Negative
RX
2 1 2 1
TX
4 3 4 3
RTS
6 5 6 5
1
CTS
8 7 8 7
RX
36 35 10 9
TX
38 37 12 11
RTS
40 39 14 13
2
CTS
42 41 16 15
RX
11 10 18 17
TX
13 12 20 19
RTS
15 14 22 21
3
CTS
17 16 24 23
RX
45 44 26 25
TX
47 46 28 27
RTS
49 48 30 29
4
CTS
51 50 32 31
RX
19 18 34 33
TX
21 20 36 35
RTS
23 22 38 37
5
CTS
25 24 40 39
RX
53 52 42 41
TX
55 54 44 43
RTS
57 56 46 45
6
CTS
59 58 48 47
RX
28 26 50 49
TX
30 29 52 51
RTS
32 31 54 53
7
CTS
34 33 56 55
RX
62 60 58 57
TX
64 63 60 59
RTS
66 65 62 61
8
CTS
68 67 64 63
DDC No. Rx-URMH 002 Rev -
Issued 12 November 2002
14 of 19
