Appendix D  

Recommended Shielded Connectors


Three alternative shielded connector systems are defined by this appendix.  
For each alternative, the connector shielding system shall provide a dc 
resistance of less than 10 milliohms from the cable shield at its termination 
point to the SCSI device enclosure.

  In order to support daisy-chain connections, SCSI devices that use shielded 
connectors should provide two shielded device connectors on the device 
enclosure.  These two connectors may be wired "one-to-one" with a stub to the 
SCSI device's drivers and receivers provided the maximum stub length is not 
violated.  Alternatively, two cables may be run from the two shielded 
connectors to the drivers and receivers so that the maximum stub length is not 
violated.  The length of the cable within the device enclosure is included 
when calculating the total cable length of the SCSI bus.

  D1 Shielded Connector, Alternative 1.  The shielded cable connector 
(Figure D1) shall be a 50-conductor connector consisting of two rows of 25 
female contacts with adjacent contacts 2.54 mm (0.1 in) apart.  The nonmating 
portion of the connector is shown for reference only.

  The shielded SCSI device connector (Figure D2) shall be a 50-conductor 
connector consisting of two rows of 25 male pins with adjacent pins 2.54 mm 
(0.1 in) apart.  The nonmating portion of the connector is shown for reference 
only.

  The connector pin assignments shall be as shown in Table 4-1 for single-
ended drivers and as shown in Table 4-2 for differential drivers.

  D2 Shielded Connector, Alternative 2.  The shielded device connector 
(Figure D3) shall be a 50-conductor connector consisting of two rows of ribbon 
contacts spaced 2.16 mm (0.085 in) apart.  The nonmating portion of the 
connector is shown for reference only.  FCC document Part 68 Subpart F 68.500 
should be used for reference.

  The shielded cable connector (Figure D4) shall be a 50-conductor connector 
consisting of two rows of ribbon contacts spaced 2.16 mm (0.085 in) apart. The 
nonmating portion of the connector is shown for reference only.

  The connector pin assignments shall be as shown in Table D1 for single-ended 
drivers and as shown in Table D2 for differential drivers.

  D3 EUROCARD Boxes  For boards in EUROCARD boxes (IEC 297 or DIN 41494) the 
EMI-screen may be in the front of the boards and in this case a screened cable 
and connector may be attached through the front panel to the board connector 
specified in section 4.3.  It is thereby possible to use the flat ribbon cable 
specified in this standard or the shielded cable, as required by users.


























































       Figure D1a. Female Shielded SCSI Cable Connector, Alternative 1

==============================================================================
Dimensions    Millimeters              Inches              
------------------------------------------------------------------------------
   A1         60.96 + 0.15             2.400 + 0.006       
   A2         66.29 + 0.18             2.610 + 0.007
   A3          2.54 + 0.15             0.100 + 0.006
   A4          2.54 + 0.15             0.100 + 0.006
   A5          8.56 + 0.41             0.337 + 0.016       
   A6         11.93 Minimum            0.470 Minimum       
   A7         65.02 + 0.18             2.560 + 0.007
   A8          5.46                    0.215               
   A9          4.14 + 0.25             0.163 + 0.010       
   A10        60.20 Maximum            2.370 Maximum       
   A11         6.60                    0.260               
   A12         1.27 Maximum            0.050 Maximum       
   A13         0.64 Maximum            0.025 Maximum       
   A14         6.604 + 0.25, - 0.13    0.260 + 0.010, - 0.005
   A15        13.46                    0.530
   A16        12.45 + 0.38             0.490 + 0.015
==============================================================================
NOTES:
  (1) Fifty Contacts on 2.54-mm (0.100-inch) spacing = 60.96 mm (2.40 inch).
  (2) Tolerances +_ 0.127 mm (0.005 inch) noncumulative, unless specified 
  otherwise.


       Figure D1b. Female Shielded SCSI Cable Connector, Alternative 1

















































































        Figure D2a. Male Shielded SCSI Device Connector, Alternative 1

==============================================================================
Dimensions    Millimeters           Inches               
------------------------------------------------------------------------------
   B1         66.65 + 0.15          2.624 + 0.006        
   B2         65.28                 2.570                
   B3          0.69                 0.027                
   B4          5.77 + 0.81          0.227 + 0.032
   B5          9.14                 0.360                
   B6          3.30                 0.130                
   B7          2.54                 0.100                
   B8          2.54                 0.100                
   B9*         2.84                 0.112                
   B10         0.15                 0.006
   B11         0.38                 0.015                
   B12         8.15 + 0.76, - 0.48  0.321 + 0.030, - 0.019
   B13         0.64 + 0.02          0.025 + 0.001        
   B14*        0.64 Square          0.025 Square
   B15        78.84                 3.104
   B16*        5.77                 0.227
   B17*        2.92                 0.115
   B18         4.83                 0.190
   B19*        3.18                 0.125
   B20*        1.52                 0.060
   B21        67.31                 2.650
   B22         9.65                 0.380
==============================================================================
NOTES:
  (1) Fifty Contacts on 2.54-mm (0.100-inch) spacing = 60.96 mm (2.40 inch).
  (2) Tolerances + 0.127 mm (0.005 inch) noncumulative, unless specified 
  otherwise.
  (3) Dimensions listed with asterisks (*) are shown for reference only.


        Figure D2b. Male Shielded SCSI Device Connector, Alternative 1










































































           Figure D3. Shielded SCSI Device Connector, Alternative 2






















































           Figure D4. Shielded SCSI Cable Connector, Alternative 2

                                   Table D1
                         Single-Ended Pin Assignments
                     (Shielded Connector, Alternative 2)

==============================================================================
                            Signal      Pin Number
------------------------------------------------------------------------------
                            -DB(0)          26
                            -DB(1)          27
                            -DB(2)          28
                            -DB(3)          29
                            -DB(4)          30
                            -DB(5)          31
                            -DB(6)          32
                            -DB(7)          33
                            -DB(P)          34
                            GROUND          35
                            GROUND          36
                            GROUND          37
                            TERMPWR         38
                            GROUND          39
                            GROUND          40
                            -ATN            41
                            GROUND          42
                            -BSY            43
                            -ACK            44
                            -RST            45
                            -MSG            46
                            -SEL            47
                            -C/D            48
                            -REQ            49
                            -I/O            50
==============================================================================
NOTES:
  (1) Pins 1_12 and 14_25 shall be connected to ground.  Pin 13 should be left 
open.  Some products designed prior to the generation of this standard 
connected this pin to ground.
  (2) The minus sign next to the signals indicates active low.

















                                   Table D2
                         Differential Pin Assignments
                     (Shielded Connector, Alternative 2)

==============================================================================
              Signal Name        Pin Number         Signal Name
------------------------------------------------------------------------------
              SHIELD GROUND      1        26        GROUND 
              +DB(0)             2        27        -DB(0) 
              +DB(1)             3        28        -DB(1) 
              +DB(2)             4        29        -DB(2) 
              +DB(3)             5        30        -DB(3) 
              +DB(4)             6        31        -DB(4) 
              +DB(5)             7        32        -DB(5) 
              +DB(6)             8        33        -DB(6) 
              +DB(7)             9        34        -DB(7) 
              +DB(P)            10        35        -DB(P) 
              DIFFSENS          11        36        GROUND 
              GROUND            12        37        GROUND 
              TERMPWR           13        38        TERMPWR
              GROUND            14        39        GROUND 
              +ATN              15        40        -ATN 
              GROUND            16        41        GROUND 
              +BSY              17        42        -BSY 
              +ACK              18        43        -ACK 
              +RST              19        44        -RST 
              +MSG              20        45        -MSG 
              +SEL              21        46        -SEL 
              +C/D              22        47        -C/D 
              +REQ              23        48        -REQ 
              +I/O              24        49        -I/O 
              GROUND            25        50        GROUND 
==============================================================================
NOTE:
  (1) SHIELD GROUND is optional on some cables.  (Implementors note:  Some 
shielded flat ribbon cables use pin 1 as a connection to the shield.)



















