EIA232
EIA232 is a standard way for serial binary communication between data terminal equipment (DTE) and data circuit terminal equipment (DCTE). The EIA232 signal are unbalanced (Single Ended), unidirectional (point-to-point) reference to ground. Normal output ranges are ±5 volts. Data is transfer in an asynchronous frame format in 8-bit binary packets. This protocol allows the system to recover quickly from errors. The EIA 232 standard is rated to operate at 20kbps. The Pin out of the DB25, DE9, and RJ45 table are as follows:
Table 1: EIA232 serial connector pin out for a DB25
DB25 Pin Number
DB25 Pin Number
DB25 Pin Number
1
-
Protective Ground
2
Out
Transmit data (Tx)
3
In
Receive data (Rx)
4
Out
Request to send (RTS)
5
In
Clear to send (CTS)
6
In
Data set ready (DSR)
7
-
Signal ground (SGND)
8
In
Data carrier detect (DCD)
9
-
Test pin
10
-
Test pin
11
-
Unassigned
12
In
Data carrier detect (CH2 only)(SDCD)
13
In
Clear to send (CH2 only)(SCTS)
14
Out
Transmit data (CH2 only)(STD)
15
Out
Transmitter clock (TCLK)(DB)
16
In
Receive data(SRD)
17
In
Receive clock (RCLK)(DD)
18
-
Local Loopback (LL)
19
Out
Request to send (CH2 only)(SRTS)
20
Out
Data terminal ready (DTR)
21
-
Signal quality detector(RL/SQ)
22
In
Ring indicator(RI)
23
Out
Data signal rate detector (CH/CI)
24
-
Auxiliary clock (CH2 only)(DA) (XCLK)
25
-
-
Figure 1 : DB25 Pin out numbering
Table 2: EIA232 serial connector pin out for a DE9
DE9 Pin Number
Direction
Pin assignment
1
In
Data carrier detect (DCD)
2
In
Receive data (Rx)
3
Out
Transmit data (Tx)
4
Out
Data terminal ready (DTR)
5
-
Signal ground
6
In
Data set ready (DSR)
7
Out
Request to send (RTS)
8
In
Clear to send (CTS)
9
In
Ring indicator(RI)
Figure 2: DE9 Pin out numbering
Table 3: DE9 to Db25 converter pin out
DE9 Pin Number
DB25 Pin Number
Pin assignment
1
8
Data carrier detect (DCD)
2
3
Receive data (Rx)
3
2
Transmit data (Tx)
4
20
Data terminal ready (DTR)
5
7
Signal ground
6
6
Data set ready (DSR)
7
4
Request to send (RTS)
8
5
Clear to send (CTS)
9
22
Ring indicator(RI)
Figure 3 : DB25 to DE9 conversion
Table 4: EIA232 serial connector pin out for a RJ-45
DE9 Pin Number
DB25 Pin Number
Pin assignment
1
In
Ring Indicator (RI)
2
In
Data carrier detect (DCD)
3
Out
Data terminal ready (DTR)
4
-
Signal Ground / Common
5
In
Receive data (Rx)
6
Out
Transmit data (Tx)
7
In
Clear to send (CTS)
8
Out
Request to send (RTS)
Figure 4 : RJ-45 Pin out
Table 4: EIA232 serial connector pin out for a RJ-45
Connector 1
Connector 2
2
3
3
2
5
5
Figure 5 : DE9 Null Modem connection
