Difference between revisions of "RS-232"
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= RS-232 = | = RS-232 = | ||
| − | RS-232 is also known as EIA-232 | + | RS-232 is also known as RS232, RS-232-C, RS-232-D, EIA-232, TIA-232E, TIA-232-F -- and even V.28/V.24 by the weirdos. There's a whole family of them. These standards are not identical, but RS-232 will get you close to what you want. In theory, the RS-232C standard only specifies the signaling, not how you actually wire it up. The pinouts given in this article are common. |
| − | The RS- | + | The RS-232C standard requires the transmitter to use +12V (0, logic low) and -12V (1, logic high). The receiver needs only see over +3V and under -3V. Most transmitting ports use only +5V and -5V. Those levels are compatible with most devices and host computers. Maxim is one of the more popular suppliers of [http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1798 RS-232 level shifters or level converters]. |
== D-sub 9 pinout (TIA-574, DE-9, and DB-9) == | == D-sub 9 pinout (TIA-574, DE-9, and DB-9) == | ||
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[[Image:DE9_Diagram.svg|thumb|100px|diagram of a DE-9 connector]] | [[Image:DE9_Diagram.svg|thumb|100px|diagram of a DE-9 connector]] | ||
| − | Technically this connector is called a '''D-sub 9''' or a '''DE-9''', but it is often | + | Technically this connector is called a '''D-sub 9''' or a '''DE-9''', but it is often incorrectly referred to as a '''DB-9'''. The '''D''' refers to the shape of the connector. The '''E''' specifies the size of the connector shell. I'm not sure why you couldn't just get that from the number of pins, but whatever... |
<pre> | <pre> | ||
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The '''D''' refers to the shape of the connector. The '''B''' specifies the size of the connector shell. | The '''D''' refers to the shape of the connector. The '''B''' specifies the size of the connector shell. | ||
| − | Note that DB-25 may carry two RS-232 lines | + | Note that DB-25 may carry two RS-232 lines, but this is rare. |
<pre> | <pre> | ||
Revision as of 01:13, 17 November 2009
Contents
RS-232
RS-232 is also known as RS232, RS-232-C, RS-232-D, EIA-232, TIA-232E, TIA-232-F -- and even V.28/V.24 by the weirdos. There's a whole family of them. These standards are not identical, but RS-232 will get you close to what you want. In theory, the RS-232C standard only specifies the signaling, not how you actually wire it up. The pinouts given in this article are common.
The RS-232C standard requires the transmitter to use +12V (0, logic low) and -12V (1, logic high). The receiver needs only see over +3V and under -3V. Most transmitting ports use only +5V and -5V. Those levels are compatible with most devices and host computers. Maxim is one of the more popular suppliers of RS-232 level shifters or level converters.
D-sub 9 pinout (TIA-574, DE-9, and DB-9)
Technically this connector is called a D-sub 9 or a DE-9, but it is often incorrectly referred to as a DB-9. The D refers to the shape of the connector. The E specifies the size of the connector shell. I'm not sure why you couldn't just get that from the number of pins, but whatever...
1 2 3 4 5 6 7 8 9
DB-25 pinout
The D refers to the shape of the connector. The B specifies the size of the connector shell. Note that DB-25 may carry two RS-232 lines, but this is rare.
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
3-wire RS-232
A minimal "3-wire" RS-232 connection consists only of TxD, RxD, and SGND (pins 3,2,5 on DB-9 and pins 2,3,7 on DB-25).
5-wire RS-232
A minimal RS-232 connection with hardware flow control: TxD, RxD, SGND, RTS, and CTS (pins 3,2,5,7,8 on DB-9 and pins 2,3,7,4,5 on DB-25).
RS-232 DB-25 to DB-9 Pinout table
| DB-25 |
DB-9 |
line |
description |
direction DTE is the computer DCE is the device |
|---|---|---|---|---|
| 1 |
shield |
ground shield |
||
| 2 |
3 |
TxD |
Transmit Data |
OUT: DTE -> DCE |
| 3 |
2 |
RxD |
Receive Data |
IN: DTE <- DCE |
| 4 |
7 |
RTS |
Request To Send |
OUT: DTE -> DCE |
| 5 |
8 |
CTS |
Clear To Send |
IN: DTE <- DCE |
| 6 |
6 |
DSR |
Data Set Ready |
IN: DTE <- DCE |
| 7 |
5 |
SGND |
signal ground |
< - > |
| 8 |
1 |
DCD |
Data Carrier Detect |
IN: DTE <- DCE |
| 9 |
||||
| 10 |
||||
| 11 |
||||
| 12 |
||||
| 13 |
||||
| 14 |
||||
| 15 |
||||
| 16 |
||||
| 17 |
||||
| 18 |
||||
| 19 |
||||
| 20 |
4 |
DT |
Data Terminal Ready |
OUT: DTE -> DCE |
| 21 |
||||
| 22 |
9 |
Rind Indicator |
IN: DTE <- DCE | |
| 23 |
||||
| 24 |
||||
| 25 |
