Serial Quick Reference Guide
10-Position Modular Jack
DB-9 Male
DB-25 Male
Pin 1
RS-232 Loopback
Pin 1
Pin 6
Pin 5
Pin 9
Pin
1
2
3
4
5
6
7
8
9
232 DTE
DCD2
RXD
TXD
DTR2
GND
DSR2
RTS
CTS
RI2
232 DCE
422/485
DCD
GND
TXD
CTS+ (HSI+)
RXD
RTS+ (HSO+)
DSR
RXD+
GND
RXD–
DTR
CTS– (HSI–)
CTS
RTS– (HSO–)
RTS
TXD+
RI
TXD–
Note: DCE mode supported on USB-232/2
and USB-232/4 only.
2 These signals are “No Connect” on the
PCI-232I and PXI-8422 ports and
ports 9–16 on legacy 16-port boards.
Pin
2
3
4
5
6
7
8
20
22
Tx
Tx
3V
Pin 1
Pin 6
Pin 5
Pin 9
Tx
–25 V
RS-485/422 Loopback
RS-485/422 Signals
MASTER
MASTER
Tx
Rx
Slave 2
Tx
120 Ω
120 Ω
120 Ω
120 Ω
Pin 1
Pin 6
Pin 5
Pin 9
All
RS-485 Voltage:
–7 V to +12 V
Dec
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Rx
Rx
For more information about LabVIEW, refer to ni.com/labview.
NI-Serial Features
Enable
4-Wire
DTR/Echo
DTR/No Echo
Auto
TX
ON
DTR
DTR
TX
RX
ON
ON
DTR
TX
Hardware
• Flexible baud rates up to 3 Mb/s
• High-performance DMA engine
• Isolation up to 2000 V
• RS-485 transceiver control
Software
• Deterministic control with
LabVIEW Real-Time
• Over 3000 instrument drivers online
• Powerful development tools
For more information about NI Serial products, refer to ni.com/serial.
For more information
about NI products,
refer to ni.com.
1
1
0
S
0
1
2
3
4
5
6
7
P
371253E-01
Idle
5V
TX–
0V
Voltages are for illustration only. Actual voltage levels may vary.
Hex
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
0x0A
0x0B
0x0C
0x0D
0x0E
0x0F
0x10
0x11
0x12
0x13
0x14
0x15
0x16
0x17
0x18
0x19
0x1A
0x1B
0x1C
0x1D
0x1E
0x1F
Char
(nul)
(soh)
(stx)
(etx)
(eot)
(enq)
(ack)
(bel)
(bs)
(tab)
(lf)
(vt)
(ff)
(cr)
(so)
(si)
(dle)
(dc1)
(dc2)
(dc3)
(dc4)
(nak)
(syn)
(etb)
(can)
(em)
(sub)
(esc)
(fs)
(gs)
(rs)
(us)
Dec
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
Hex
0x20
0x21
0x22
0x23
0x24
0x25
0x26
0x27
0x28
0x29
0x2A
0x2B
0x2C
0x2D
0x2E
0x2F
0x30
0x31
0x32
0x33
0x34
0x35
0x36
0x37
0x38
0x39
0x3A
0x3B
0x3C
0x3D
0x3E
0x3F
Char
(sp)
!
“
#
$
%
&
‘
(
)
*
+
,
.
/
0
1
2
3
4
5
6
7
8
9
:
;
<
=
>
?
Dec
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
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Notice at ni.com/patents. You can find information about end-user license agreements (EULAs) and third-party legal notices in the readme file for your NI product. Refer to the Export Compliance Information at ni.com/
legal/export-compliance for the National Instruments global trade compliance policy and how to obtain relevant HTS codes, ECCNs, and other import/export data.
© 2004–2013 National Instruments. All rights reserved.
S
ASCII Table
4-Wire Full-Duplex Multidrop Network Using Terminating Resistors
2-Wire
0
0V
RS-422 Voltage: ±7 V
RS-485 terminators are available at ni.com/serial.
RS-485 Transceiver Control
1
TX+
Slave n
Tx
Rx
1
–5 V
If '–' > '+'
then SPACE, '0'
TX/RX
2-Wire Multidrop Network Using Terminating Resistors
Rx
0
RS-485
5V
If '–' < '+'
then MARK, '1'
Pin 5
Pin 9
Pin 1
Pin 6
120 Ω
120 Ω
0
RS-232
+5 V
MARK, '1'
All
Rx
Slave 1
Idle
–3 V
Slave n
Rx
1
UNKNOWN
Tx
Tx
Data
LabVIEW Programming Example
Slave 2
Rx
422/485
RTS+ (HSO+)
CTS+ (HSI+)
RTS– (HSO–)
TXD+
CTS– (HSI–)
RXD–
GND
RXD+
TXD–
Pins not listed in this table are
“No Connect.”
3 These signals are “No Connect”
on the PCI-232I and PXI-8422
ports.
RS-485 Topologies
Slave 1
Pin 25
232
TXD
RXD
RTS
CTS
DSR3
GND
DCD3
DTR3
RI3
UART Data Frame Example
0xD9—8 Data Bits, Odd Parity, 1 Stop Bit
SPACE, '0'
TX/RX
Pin 14
Pin
232
422/485
1
No Connect
No Connect
TXD–
2
RI1
3
CTS
TXD+
4
RTS
RTS– (HSO–)
CTS– (HSI–)
5
DSR1
6
GND
RXD–
RXD+
7
DTR1
8
TXD
RTS+ (HSO+)
9
RXD
CTS+ (HSI+)
GND
10
DCD1
1 These signals are “No Connect”
on the PCI-232I and PXI-8422
ports.
Pin 5
Pin 9
Pin 1
Pin 6
Pin 10
RS-232 Signals
25 V
Pin 13
Pin 1
Jul13
Hex
0x40
0x41
0x42
0x43
0x44
0x45
0x46
0x47
0x48
0x49
0x4A
0x4B
0x4C
0x4D
0x4E
0x4F
0x50
0x51
0x52
0x53
0x54
0x55
0x56
0x57
0x58
0x59
0x5A
0x5B
0x5C
0x5D
0x5E
0x5F
Char
@
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
[
\
]
^
_
Dec
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
Hex
0x60
0x61
0x62
0x63
0x64
0x65
0x66
0x67
0x68
0x69
0x6A
0x6B
0x6C
0x6D
0x6E
0x6F
0x70
0x71
0x72
0x73
0x74
0x75
0x76
0x77
0x78
0x79
0x7A
0x7B
0x7C
0x7D
0x7E
0x7F
Char
‘
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z
{
|
}
~
(del)