RS-232 Connectors

RS-232 Connectors

The Electronic Industries Association (EIA) RS-232 specification, specifies pin-outs on a 25 pin subminiature D series connector, a DB-25. When the PC was introduced the RS-232 serial communications port was implemented on a 9 pin subminiature D series connector, a DE-9.

The interface is a single ended interface and as such is only useful for short distances of 50 feet or less. The maximum length depends on the baud rate and the type of cable used.

Data Communications Equipment (DCE)

Data Communication Equipment is any equipment to be used to facilitate the exchange of data. This typically includes Modems and other such like equipment.

Data Terminal Equipment (DTE)

Data Terminal Equipment is any type of used at the end of the communication link. This typically includes Computer Terminals, Personal Computers (PC), Printers and other such like equipment.

DE-9 RS-232 Pinouts
DTE - PC Comm Port

PC Comm Port, RS-232, DE-9 Male
PinDirSignalFunction
1
In
DCDData Carrier Detect
2
In
RXDReceive Data
3
Out
TXDTransmit Data
4
Out
DTRData Terminal Ready
5
--
GNDGround
6
In
DSRData Set Ready
7
Out
RTSRequest to Send
8
In
CTSClear to Send
9
In
RIRing Indicator

The standard PC Serial Communications port is brought out on a DE-9 male connector. Below is a table showing the Pin-outs for the Comm prot

DE-9 RS-232 Pinouts
DCE - Priferal

PC Comm Port, RS-232, DE-9 Male
PinDirSignalFunction
1
In
DCDData Carrier Detect
2
Out
TXDTransmit Data
3
In
RXDReceive Data
4
Out
RTSRequest to Send
5
--
GNDGround
6
In
DSRData Set Ready
7
Out
DTRData Terminal Ready
8
In
CTSClear to Send
9
In
RIRing Indicator

The standard PC Serial Communications port is brought out on a DE-9 male connector. Below is a table showing the Pin-outs for the Comm prot

DE-9 RS-232 Pinouts
PC Standard

The standard PC Serial Communications port is brought out on a DE-9 male connector.

DB-25 RS-232 Pin-outs
DTE

RS-232 DTE Pinouts
PinDirSignalFunction
1
--
GNDFreame ground
2
Out
TXDTransmit Data
3
In
RXDReceive Data
4
Out
RTSRequest to Send
5
In
CTSClear to Send
6
In
DSRData Set Ready
7
--
GNDSignal Ground
8
In
CDCarrier Detect
9
--
--Reserved
10
--
--Reserved
11
Out
STFSelect Transmit Channel
12
In
SCDSecondary Carrier Detect
13
In
SCTSSecondary Clear to Send
14
Out
STXDSecondary Transmit Data
15
In
TCKTransmission Signal Element Timing
16
In
SRXDSecondary Receive Data
17
In
RCKReceiver Signal Element Timing
18
Out
LLLocal Loop Control
19
Out
SRTSSecondary Request to Send
20
Out
DTRData Terminal Ready
21
Out
RLRemote Loop Control
22
In
RIRing Indicator
23
Out
DSRSData Signal Rate Selector
24
Out
XCKTransmit Signal Element Timing
25
In
TITest Indicator

Serial Connections for Data Terminal Equipment (DTE)

DB-25 RS-232 Pin-outs
DCE

RS-232 DCE Pinouts
PinDirSignalFunction
1
--
GNDFreame ground
2
Out
TXDTransmit Data
3
In
RXDReceive Data
4
Out
RTSRequest to Send
5
In
CTSClear to Send
6
In
DSRData Set Ready
7
--
GNDSignal Ground
8
In
CDCarrier Detect
9
--
--Reserved
10
--
--Reserved
11
Out
STFSelect Transmit Channel
12
In
SCDSecondary Carrier Detect
13
In
SCTSSecondary Clear to Send
14
Out
STXDSecondary Transmit Data
15
In
TCKTransmission Signal Element Timing
16
In
SRXDSecondary Receive Data
17
In
RCKReceiver Signal Element Timing
18
Out
LLLocal Loop Control
19
Out
SRTSSecondary Request to Send
20
Out
DTRData Terminal Ready
21
Out
RLRemote Loop Control
22
In
RIRing Indicator
23
Out
DSRSData Signal Rate Selector
24
Out
XCKTransmit Signal Element Timing
25
In
TITest Indicator

Serial Connections for Data Terminal Equipment (DCE)

Standard DB-25 RS-232 Pinouts

The standard RS-232 Communications port is brought out on a DB-25 male connector.

The standard RS-232 Communications port is brought out on a DB-25 male connector.

RS-422 Connections

RS-422 Connectors

The interface is a differential interface and as such is only useful for distances of 2000 feet or less at a BAUD rate of 56Kbps, when using appropriate type of cable. However the maximum cable length is not specified in the standard.

Sony P2 Connectors

Sony defines the two devices Controlled Device and Controlling Device. The controling device is a Editing system, Automation System or other user control interface.

The Controled interface is a tape machine, video server or other devices intended to be controled. Controlling Device, DE-9 RS422 Pinouts.

Controling Device,
DE-9 RS-422 Pinouts

Controling Device
PinDirectionSignalFunction
1
--
GNDGround for RS-422 and/or external power
2
In
RX-Receive Data, minus (input)
3
Out
TX+Transmit Data, plus (output)
4
--
--Not Used
5
--
GNDground for RS-422 and/or external power
6
--
--Not Used
7
In
RX+Receive Data, plus (input)
8
Out
TX-Transmit Data, minus (output)
9
--
+VOptional +5V to +12V DC @ 100ma

The TX and RX signals as well as the pin 1 ground follow the SMPTE standard. Below is a table showing the Pinouts for the Controled Device

Controled Device,
DE-9 RS-422 Pinouts

Controlled Device
PinDirectionSignalFunction
1
--
GROUNDground for RS-422 and/or external power
2
Out
TX-Transmit Data, minus (output)
3
In
RX+Receive Data, plus (input)
4
--
--Not Used
5
--
GROUNDground for RS-422 and/or external power
6
--
--Not Used
7
Out
TX+TransmitData, plus (output)
8
In
RX-Receice Data, minus (input)
9
--
+VOptional +5V to +12V DC @ 100ma

The TX and RX signals as well as the pin 1 ground follow the SMPTE standard. Below is a table showing the Pinouts for the Controled Device

Sony P2 Device Control,
DE-9 RS-422 Pinouts

Sony defines the two devices Controlled Device and Controlling Device. The controling device is a Editing system, Automation System or other user control interface.

The Controled interface is a tape machine, video server or other devices intended to be controled.

P2 Communications Format

P2 Protocol is Asynchronous serial communications

  • 38.4Kb/s
  • 1 Start bit
  • 8 Data bits
  • 1 Parity bit (odd parity)
  • 1 Sotp bit