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Author Topic: EIA-232 (formerly known as RS-232) pinouts  (Read 3949 times)

Dave Loucks

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EIA-232 (formerly known as RS-232) pinouts
« on: June 20, 2012, 06:17:43 AM »
25-pin EIA-232 Port

Pin No.NameDirNotes/Description
1PGNDINProtective ground.  Cable shield connected here.
2TDOUTTransmit Data (a.k.a TxD, Tx). Sending data to DCE from DTE.
3RDINReceive Data (a.k.a RxD, Rx). Arriving data from DCE.
4RTSOUTRequest to Send.  Raised by DTE when it wishes to send.  Expects CTS from DCE.
5CTSINClear to Send. Raised by DCE in response to RTS from DTE
6DSRINData Set Ready. Raised by DCE to indicate ready.
7SGND-Signal ground / common for all other signals.
8DCDINData Carrier Detect. Raised by DCE when modem synchronized.
9+OUT+VOLTAGE.  Defined but typically not implemented.
10-OUT-VOLTAGE.  Defined but typically not implemented.
11--Unassigned pin.  No connection.
12sDCDINSecondary Data Carrier Detect (or Received Line Signal Detector)
13sCTSINSecondary Clear To Send.
14sTDOUTSecondary Transmit Data (sTxD).
15TSETINTransmitter Signal Element Timing.
16sRDINSecondary Received Data (sRxD).
17RSETINReceiver Signal Element Timing.
18LLOUTLocal Loopback.
19sRTSOUTSecondary Request To Send.
20DTROUTData Terminal Ready.  Typically raised when the data terminal (PC or PLC) is powered and ready.
21RLOUTRemote Loopback.
22RIINRing Indicate.  Raised by DCE and sent to DTE to tell DTE to get ready... a call is coming.
23sCTS-Data Signal Rate Selector. Can sent by either DCE or DTE.
24ETSETOUTExternal Transmit Signal Element Timing.
25TMINTest Mode.

9-pin EIA-232 Port

Pin No.NameDirNotes/Description
1DCDINData Carrier Detect. Raised by DCE when modem synchronized.
2RDINReceive Data (a.k.a RxD, Rx). Arriving data from DCE.
3TDOUTTransmit Data (a.k.a TxD, Tx). Sending data from DTE.
4DTROUTData Terminal Ready. Raised by DTE when powered on. In auto-answer mode raised only when RI arrives from DCE.
5SGND-Ground
6DSRINData Set Ready. Raised by DCE to indicate ready.
7RTSOUTRequest To Send. Raised by DTE when it wishes to send. Expects CTS from DCE.
8CTSINClear To Send. Raised by DCE in response to RTS from DTE.
9RIINRing Indicator. Set when incoming ring detected - used for auto-answer application. DTE raised DTR to answer.