Sun Serial Port & Cable Pinouts

[Last updated May 18, 2001]

Port voltage: Many Sun cpu serial ports can be configured as either RS-232 (+/- 12V) or RS-423 (+/- 5V). Defaults vary. See the hardware documentation for your machine to locate the jumper to configure this, if it exists. Most implementations do not have to worry about the voltage on the serial port.

Port splitter cable: Many Suns need a Y-cable to split the A/B Serial Port into the 2 different devices. Different Suns use different splitter cables for this purpose. Some Suns use small, round Mini DIN8 connectors that require an adapter to connect to a DB25 device, like a modem or terminal. Pinouts are shown below.

Not all Suns are represented here. If you have the pinout of a Sun not listed, please send it to webmistress@stokely.com and she'll include it in this list.

Serial Port & Cable Pinouts

ELC/SLC
SparcStation 2
Ultra 1, 2, 30, 60, Enterprise 150/ 220R/ 250/ 6500/ 5500/ 4500/ 3500/ 3000

Enterprise 420R
Ultra 5, 10
Netra t1 Model 105/ AC200/ DC200
IPC/IPX

Sparc 4, 10, 20, LX, Classic, Classic X, Ultra Enterprise 450
Ultra 80, Sun Blade 1000
Sun Blade 100

Null modem, DB25/DB25
Null modem, DB25/DB9
Null terminal DB25/DB25
Null terminal DB25/DB9

New Keyboard, mouse, video

Pin Identification

db-25 male  db-25 female  db-9 male  db-9 female 
rj45 rj45 male  din8m   

Webmistress' comments on cable vendors:

Sun ELC and SLC CPU serial ports: The Sun part number is for the ELC serial port splitter cable is X985Q. The SLC serial port splitter cable is Sun part # 530-1667. The pinout below is from the May 1993 Sun FE Handbook.

Pin  Signal  Port     Pin  Signal  Port
-----------------     -----------------
2    TD      A        13   CTS     B
3    RD      A        14   TD      B
4    RTS     A        15   TC      A
5    CTS     A        16   RD      B
6    DSR     A        17   RC      A
7    GND     A        19   RTS     B
8    DCD     A        20   DTR     A
12   DCD     B        24   TCO     A

SparcStation 2: The SparcStation 2 has 2 DB25, 25-pin serial ports:

Pin Signal  Description
--- ------  -----------
2   TxD     output
3   RxD     input
4   RTS     output
5   CTS     input
6   DSR     input
7   GND
8   DCD     input
20  DTR     output

Ultra 1, 2, 30, 60, Enterprise 150/ 220R/ 250/ 6500/ 5500/ 4500/ 3500/ 3000: These machines have 2 DB25, 25-pin RS-423/RS-232 serial ports:

Pin   Signal      Description
---   ------      -----------
2     TxD output  Transmit Data
3     RxD input   Receive Data
4     RTS output  Request to Send
5     CTS input   Clear to Send
6     DSR input   Data Set Ready
7     GND         Ground
8     DCD input   Data Carrier Detect
9-14  none        Not connected
15    TRxC input1 Transmit Clock input1
16    none        Not connected
17    RTxC input2 Receive Clock2
18-19 none        Not connected
20    DTR output  Data Terminal Ready
21-23 none        Not connected
24    TxC output3 Transmit Clock output3
25    none        Not Connected

Notes:
1 Enterprise 6500/5500/4500/3500/3000 labels this as DB.
2 Enterprise 6500/5500/4500/3500/3000 labels this as DD.
3 Enterprise 6500/5500/4500/3500/3000 labels this as DA.

Enterprise 420R: This machine has 2 DB25, 25-pin RS-423/RS-232 serial ports:

Pin    Signal        Description
---    ------        -----------
2      TxD output    Transmit Data
3      RxD input     Receive Data
4      RTS output    Request to Send
5      CTS input     Clear to Send
6      DSR input     Data Set Ready
7      GND           Ground
8      DCD input     Data Carrier Detect
9      BUTTON_POR    To be determined
10     BUTTON_XIR_L  To be determined
11     +5Vdc         +5 VDC
12-14  none          Not connected
15     TRxC input    Transmit Clock
16     none          Not connected
17     RTxC input    Receive Clock
18-19  none          Not connected
20     DTR output    Data Terminal Ready
21-23  none          Not connected
24     TxC output    Transmit Clock
25     none          Not Connected

Ultra 5 & 10: Port A is a DB25, Port B is a DB9:

Serial Port A (DB25) 
Pin   Signal      Description
---   ------      -----------
2     TxD output  Transmit Data
3     RxD input   Receive Data
4     RTS output  Request to Send
5     CTS input   Clear to Send 
6     DSR input   Data Set Ready
7     GND         Ground       
8     DCD input   Data Carrier Detect
9-14  none        Not connected     
15    TRxC input  Transmit Clock   
16    none        Not connected
17    RTxC input  Receive Clock
20    DTR output  Data Terminal Ready
21-23 none        Not connected
24    TxC output  Transmit Clock
25    none        Not Connected

Serial Port B (DB9)
Pin   Signal      Description
---   ------      -----------
1     CD          Carrier Detect
2     RD          Receive Data
3     TD          Transmit Data
4     DTR         Data Terminal Ready
5     GND         Ground
6     DSR         Data Set Ready
7     RTS         Request to Send
8     CTS         Clear to Send
9     RI          Ring Indicator

Netra t1 Model 105/AC200/DC200: The Netra has RJ-45 connectors for serial ports.

           RJ45 Connector
    ------------------------------
    1 - RTS          5 - REF (GND) 
    2 - DTR          6 - RXD
    3 - TXD          7 - DSR
    4 - REF (GND)    8 - CTS

Below are pinouts for a Netra RJ45 - DB25 RS232 serial converter cable, part number 530-2889-01 and a hand-crafted Netra RJ45 - DB9 serial cable. (There is also a part number 530-2889-01 which has the same pinout except that the RJ-45 BODY (black) is wired to RS232 pin 1 GND.)

Note that these are wired DCE. If you use the supplied Netra RJ-45 to DB25 RS232 adapter, you get a null-modem cable, suitable for a terminal connection. Use a null-modem adapter or a rollover RJ-45 cable to connect this adapter to a modem. (The webmistress has received conflicting information on the supplied Netra adapter. Verify your pinout before you rely on it.)

  Netra                 Sun serial DB25
  RJ-45                 RS-232 adapter 
  Pin                   part # 530-2889-01
  --------------        ------------------
  1 (RTS) blue    ---   5  (CTS)
  2 (DTR) orange  ---   6  (DSR)
  3 (TXD) black   ---   3  (RXD)
  4 (GND) red     ---   7  (GND)      
  5 (GND) green   ---   7  (GND)
  6 (RXD) yellow  ---   2  (TXD)
  7 (DSR) brown   ---   20 (DTR)
  8 (CTS) gray    ---   4  (RTS)
  Netra                 DB9 adapter
  RJ-45                 RS-232 Pin
  Pin                   (make your own cable)
  --------------        ---------------------
  1 (RTS) blue    ---   8 (CTS)
  2 (DTR) orange  ---   6 (DSR)
  3 (TXD) black   ---   2 (RXD)
  4 (GND) red     ---   5 (GND)      
  5 (GND) green   ---   5 (GND)
  6 (RXD) yellow  ---   3 (TXD)
  7 (DSR) brown   ---   4 (DTR)
  8 (CTS) gray    ---   7 (RTS)

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Sun IPC and IPX CPU serial ports: Sun no longer sells the serial DIN8 to DB25 serial cable part. It's available for about US$28 from Ultra Spec Cables.

Macintosh serial cables may also work for terminal connections (if lines 2 and 3 are crossed, as in a null-modem cable), but not for modem connections, since the Macintosh cable has no DCD line. There are several different Mac modem cables, so check that the pinout matches what you need. If you feel we're wrong on this Mac cable issue, please convince us via email to webmistress@stokely.com.

Note that DB25 pin 6, 15, 22, 24, and 25 are not supported on the Sun serial port adapter cable. The left pinout below is taken from the SparcStation IPC Installation Guide.

IPC & IPX DB25 to DIN8 Cable Pinout

DIN8      DB25       Signal  Description
Pin       Pin
----------------------------------------
1         20         DTR     Data Terminal Ready
2         5          CTS     Clear to Send
3         2          TXD     Transmit Data
4         7          GND     Ground
5         3          RXD     Receive Data
6         4          RTS     Request to Send
7         8          DCD     Data Carrier Detect
8         17         RTXC    Receive Clock
N/A       6          DSR     Data Set Ready, not used
N/A       15         DB      Transmit Clock, not used
N/A       22         RI      Ring Indicator, not connected
N/A       24         DA      Transmit Clock, not used
N/A       25         -       Not connected

Mini DIN8 MacintoshPlus Serial Cable Pinout
(One of many Mac serial cables. Not all will work.)

Pin  Signal      Description
----------------------------
1    HSKo        Output Handshake (Zilog 8530 DTR pin)
2    HSKi/CLK    Input Handshake *OR* External Clock
3    TxD-        Transmit data (-)
4    Ground      Signal ground
5    RxD-        Receive data (-)
6    TxD+        Transmit data (+)
7    N/C         (no connection)
8    RxD+        Receive data (+)

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Sun Sparcstation 4, 10, 20, LX, Classic, Classic X, & Ultra Enterprise 450 CPU serial ports:

Y-cable (Sun Part number X985A) and the DB25 connector on the system unit, labeled A/B.

Reprinted from the Sun Microsystem Inc.'s Desktop SPARC Hardware Owner's Guide (Dec '92) and other information. This is the pinout of the Serial Port A/B connector and the Ports A and B of the Y-Cable that attach to it.

Legend: x = active pins, o = inactive pins (or pin not there)

E450 tidbit: The E450 has its serial port set to RS-423 (+/- 5v) by default. To change it to RS-232 (+/- 12v), move the jumper at J3303 (near the parallel port) from pins 2-3 to pins 1-2. This is seldom necessary with modern serial devices, because most devices can use either voltage set. But, there are those rare times when some strange device cares about the serial port voltage.

Sun Sparcstation 4, 5, 10, 20, LX, Classic, Classic X & Ultra Enterprise 450:
System Unit Back Panel Serial Connector Pinout

  1  1  1  1                   
  3  2  1  0  9  8  7  6  5  4  3  2  1
-----------------------------------------
| x  x  x  o  o  x  x  x  x  x  x  x  o |
| x  x  o  o  o  x  x  x  x  x  x  x    |
-----------------------------------------
  2  2  2  2  2  2  1  1  1  1  1  1
  5  4  3  2  1  0  9  8  7  6  5  4

Pin    Circuit  Signal  Direction  Description
---    -------  ------  ---------  -----------
1      none     none    --         not connected
2      BA       TD      output     Transmit Data, Port A
3      BB       RD      input      Receive Data, Port A
4      CA       RTS     output     Request to Send, Port A
5      CB       CTS     input      Clear to Send, Port A
6      CC       DSR     input      Data Set Ready, Port A
7      AB       SG      --         Signal Ground
8      CF       DCD     input      Data Carrier Detect, Port A
9-10   none     none    --         not connected
11     SCD      SDTR    input      Data Terminal Ready, Port B
12     SCF      SDCD    input      Data Carrier Detect, Port B
13     SCB      SCTS    input      Clear to Send, Port B
14     SBA      STD     output     Transmit Data, Port B
15     DB       TC      input      Transmit Clock, Port A 
                                   DCE source
16     SBB      SRD     input      Receive Data, Port B
17     DD       RC      input      Receive Clock, Port A
18     SDB      STC     input      Transmit Clock, Port B
19     SCA      SRTS    output     Request to Send, Port B
20     CD       DTR     output     Data Terminal Ready, Port A
21-23  none     none    --         not connected
24     DA       TC      output     Transmit Clock, Port A 
                                   DTE source
25     DA       TC      output     Transmit Clock, Port B 
                                   DTE source

Sun Sparcstation 4, 5, 10, 20, LX, Classic, Classic X & Ultra Enterprise 450:
Serial Interface Y-Cable Port A Specifications - Synchronous & Asynchronous

  1  1  1  1                   
  3  2  1  0  9  8  7  6  5  4  3  2  1
-----------------------------------------
| o  o  o  o  o  x  x  x  x  x  x  x  o |
| o  x  o  o  o  x  o  o  x  o  x  o    |
-----------------------------------------
  2  2  2  2  2  2  1  1  1  1  1  1
  5  4  3  2  1  0  9  8  7  6  5  4

Pin  Circuit  Signal  Direction  Description
---  -------  ------  ---------  -----------
2     BA      TD      output     Transmit Data
3     BB      RD      input      Receive Data
4     CA      RTS     output     Request to Send
5     CB      CTS     input      Clear to Send
6     CC      DSR     input      Data Set Ready
7     AB      SG      --         Signal Ground
8     CF      DCD     input      Data Carrier Detect
15    DB      TC      input      Transmit Clock, 
                                 DCE source
17    DD      RC      input      Receive Clock
20    CD      DTR     output     Data Terminal Ready
24    DA      TC      output     Transmit Clock, 
                                 DTE Source

Sun Sparcstation 4, 5, 10, 20, LX, Classic, Classic X & Ultra Enterprise 450:
Serial Interface Y-Cable Port B Specifications - Asynchronous Only

  1  1  1  1                   
  3  2  1  0  9  8  7  6  5  4  3  2  1
-----------------------------------------
| o  o  o  o  o  x  x  o  x  x  x  x  o |
| o  o  o  o  o  x  o  o  o  o  o  o    |
-----------------------------------------
  2  2  2  2  2  2  1  1  1  1  1  1
  5  4  3  2  1  0  9  8  7  6  5  4

Pin  Circuit  Signal  Direction  Description 
---  -------  ------  ---------  ----------- 
2    BA       TD      output     Transmit Data 
3    BB       RD      input      Receive Data 
4    CA       RTS     output     Request to Send 
5    CB       CTS     input      Clear to Send      
7    AB       SG      --         Signal Ground 
8    CF       DCD     input      Data Carrier Detect 
20   CD       DTR     output     Data Terminal Ready 

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Ultra 80 & Sun Blade 1000 CPU serial ports: The serial port A and B connectors are DB25 connectors located on the motherboard back panel. The 2 ports are wired in the same way.

Pin    Signal             Description
---    ------             -----------
1      NC                 Not connected  
2      SER_TDX_A_CONN     Transmit data  
3      SER_RXD_A_CONN     Receive data  
4      SER_RTS_A_L_CONN   Ready to send  
5      SER_CTS_A_L_CONN   Clear to send  
6      SER_DSR_A_L_CONN   Data set ready  
7      GND                Signal ground  
8      SER_DCD_A_L-CONN   Data carrier detect  
9      BUTTON_POR         Power-on reset  
10     BUTTON_XIR_L       Transmit internal reset  
11     +5VDC              +5 VDC  
12-14  NC                 Not connected  
15     SER_TRXC_A_L_CONN  Transmit clock  
16     NC                 Not connected  
17     SER_RXC_A_L_CONN   Receive clock  
18-19  NC                 Not connected  
20     SER_DTR_A_L_CONN   Data terminal ready  
21-23  NC                 Not connected  
24     SER_TXC_A_L_CONN   Terminal clock  
25     NC                 Not connected  

Sun Blade 100 CPU serial port: The 1 serial port connector is a DB9 type connector located on the back panel. The serial port connector provides asynchronous serial communications.

Pin  Signal  Description
---  ------  -----------
1    CD      Carrier detect  
2    RD      Receive data  
3    TD      Transmit data  
4    DTR     Data terminal ready  
5    GND     Ground  
6    DSR     Data set ready  
7    RTS     Request to send  
8    CTS     Clear to send  
9    RI      Ring indicator  

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Null Modem & Null Terminal Pinouts

Null modem pinout DB25 to DB25: Used in connecting 2 computers with full modem signalling capability. This is usually the pinout found in null modem cables for DB25 to DB25.

DB25                   DB25
-----                  -----
1 GND  --------------- 1 GND
2 TD   --------------- 3 RD
3 RD   --------------- 2 TD
4 RTS  --------------- 5 CTS
5 CTS  --------------- 4 RTS
7 GND  --------------- 7 GND
6 DSR  ---+
          +----------- 20 DTR
8 DCD  ---+
                 +---- 6 DSR
20 DTR ----------+
                 +---- 8 DCD

Null modem pinout DB25 to DB9: Used in connecting 2 computers with full modem signalling capability. This is usually the pinout found in null modem cables for DB25 to DB9.

DB25        DB9
----        ---
1 GND  ---  1 GND
2 TD   ---  2 RD
3 RD   ---  3 TD
4 RTS  ---  8 CTS
5 CTS  ---  7 RTS
7 GND  ---  5 GND
6 DSR  ---  4 DTR
20 DTR ---  6 DSR

Null terminal pinout DB25 to DB25: Used in connecting 2 computers without modem signalling capability. You usually have to build this cable yourself.

DB25        DB25
----        ----
1 GND  ---  1 GND (optional, but a Very Good Idea)
2 TD   ---  3 RD
3 RD   ---  2 TD
7 GND  ---  7 GND

Null terminal pinout DB25 to DB9: Used in connecting 2 computers without modem signalling capability. You usually have to build this cable yourself.

DB25        DB9
----        ---
1 GND  ---  1 GND (optional, but a Very Good Idea)
2 TD   ---  2 RD
3 RD   ---  3 TD
7 GND  ---  5 GND

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Sun Keyboard and mouse pinouts, Sun and SGI video:

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