.
RS232 DB25 pinout
RS232 DB25 pinout description
Pin No. | Name | Dir | Notes/Description |
1 | - | - | Protective/shielded ground |
2 | TD | OUT | Transmit Data (a.k.a TxD, Tx) (ASYNC) |
3 | RD | IN | Receive Data (a.k.a RxD, Rx) (ASYNC) |
4 | RTS | OUT | Request To Send (ASYNC) |
5 | CTS | IN | Clear To Send (ASYNC) |
6 | DSR | IN | Data Set Ready (ASYNC) |
7 | SGND | - | Signal Ground |
8 | CD | IN | Carrier Detect (a.k.a DCD). |
9 | - | - | Reserved for data set testing. |
10 | - | - | Reserved for data set testing. |
11 | - | - | Unassigned |
12 | SDCD | IN | Secondary Carrier Detect. Only needed if second channel being used. |
13 | SCTS | IN | Secondary Clear to send. Only needed if second channel being used. |
14 | STD | OUT | Secondary Transmit Data. Only needed if second channel being used. |
15 | DB | OUT | Transmit Clock (a.k.a TCLK, TxCLK). Synchronous use only. |
16 | SRD | IN | Secondary Receive Data. Only needed if second channel being used. |
17 | DD | IN | Receive Clock (a.k.a. RCLK). Synchronous use only. |
18 | LL | - | Local Loopback |
19 | SRTS | OUT | Secondary Request to Send. Only needed if second channel being used. |
20 | DTR | OUT | Data Terminal Ready. (ASYNC) |
21 | RL/SQ | - | Signal Quality Detector/Remote loopback |
22 | RI | IN | Ring Indicator. DCE (Modem) raises when incoming call detected used for auto answer applications. |
23 | CH/CI | OUT | Signal Rate selector. |
24 | DA | - | Auxiliary Clock (a.k.a. ACLK). Secondary Channel only. |
25 | - | - | Unassigned |
Electronic Circuits:
Circuit Diagram:
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