การ Interface กับ Serial Port (Part II)Serial Pinouts (DB25 & DB9)
Serial Port มีขั้วต่อ 2 แบบคือ แบบ D-Type 25 Pin และแบบ D-Type 9 Pin ซึ่งทั้ง
2 แบบ จะเป็นชนิดตัวผู้ทางด้านของ Computer ดังนั้นอุปกรณ์ที่จะนำมาต่อกับ Computer
จึงต้องใช้ขั้วต่อชนิดตัวเมีย Table 1. ข้างล่างแสดง ชื่อสัญญาณของขาต่าง ๆ
(Male at the computer side)
(Female at the cable side)
25 PIN D-SUB MALE at the computer.
| Pin |
Name |
Dir |
Description |
| 1 |
SHIELD |
--- |
Shield or Protective Ground |
| 2 |
TXD |
--> |
Transmit Data |
| 3 |
RXD |
<-- |
Receive Data |
| 4 |
RTS |
--> |
Request to Send |
| 5 |
CTS |
<-- |
Clear to Send |
| 6 |
DSR |
<-- |
Data Set Ready |
| 7 |
GND |
--- |
Signal Ground |
| 8 |
CD |
|
Carrier Detect |
| 9 |
n/c |
- |
Reserved for Data Set Testing |
| 10 |
n/c |
- |
Reserved for Data Set Testing |
| 11 |
n/c |
- |
Unassigned |
| 12 |
|
<-- |
Secondary Carrier Detect |
| 13 |
|
<-- |
Secondary Clear to Send |
| 14 |
|
--> |
Secondary Transmit Data |
| 15 |
|
<-- |
Transmit Signal Element Timing (DCE) |
| 16 |
|
<-- |
Secondary Recieve Data |
| 17 |
|
<-- |
Recieve Signal Element Timing (DCE) |
| 18 |
n/c |
- |
Unassigned |
| 19 |
|
--> |
Secondary Request to Send |
| 20 |
DTR |
--> |
Data Terminal Ready |
| 21 |
|
<-- |
Signal Quality Detect |
| 22 |
RI |
<-- |
Ring Indicator |
| 23 |
|
<-> |
Data Signal Rate Select (DCE/DTE) |
| 24 |
|
--> |
Transmit Signal Element Timing (DTE) |
| 25 |
n/c |
- |
Unassigned |
Note: Direction is DTE (Computer) relative DCE
(Modem).
Note: Do not connect SHIELD(1) to GND(7).
Note: The red colored signal is rarely use.
(Male at the computer side) (Female at the cable side)
9 PIN D-SUB MALE at the Computer.
| Pin |
Name |
RS232 |
V.24 |
Dir |
Description |
| 1 |
CD |
CF |
109 |
<----- |
Carrier Detect |
| 2 |
RXD |
BB |
104 |
<----- | Receive Data |
| 3 |
TXD |
BA |
103 |
------> |
Transmit Data |
| 4 |
DTR |
CD |
108.2 |
------> |
Data Terminal Ready |
| 5 |
GND |
AB |
102 |
-------- |
Signal Ground |
| 6 |
DSR |
CC |
107 |
<------ |
Data Set Ready |
| 7 |
RTS |
CA |
105 |
------> |
Request to Send |
| 8 |
CTS |
CB |
106 |
<------ |
Clear to Send |
| 9 |
RI |
CE |
125 |
<------ |
Ring Indicator |
Note: Direction is DTE (Computer) relative DCE
(Modem).
Note: RS232 column is RS232 circuit name.
Note: V.24 column is
ITU-TSS V.24 circuit name.
Table 1. D-Type 25 and D-Type 9
Connector
|
Pin No. (D-Type 25) |
Pin No. (D-Type 9) |
Abbreviation |
Full Name |
|
2 |
3 |
TD |
Transmit Data |
|
3 |
2 |
RD |
Receive Data |
|
4 |
7 |
RTS |
Ready To Send |
|
5 |
8 |
CTS |
Clear To Send |
|
6 |
6 |
DSR |
Data Set Ready |
|
7 |
5 |
SG |
Signal Ground |
|
8 |
1 |
(D)CD |
(Data) Carrier Detect |
|
20 |
4 |
DTR |
Data Terminal Ready |
|
22 |
9 |
RI |
Ring Indicator |
| 
