Conference 7.286::fddi

    The DEFPA documentation shows the correct wiring. This is the
    same wiring as used in the DEFBA DECswitch 900EF.
    Thus in the instance where a 6-pin MJ connector is used, the
    pinnout is...
    
    pin      assignment
    ---      ----------
    
    1,2      Relay drive +5v (200ma max)
    3,4,6    Return grounded internally
    5        Bypass present (must be externally grounded to pin 3,4, or 6)
    
    I'm looking at AMP bulletin IS 9503, and it shows 3 types of connectors
    that they sell their FDDI Dual Bypass Switch #501916-1, -2 -3 with.
    These three variations of their bypass switch come with a 6 pin din,
    a 6 pin MTE receptacle, or a 6 pin MJ connector.
    In all three descriptions of the power connector wiring, AMP was
    very careful to use the same pin number in all three types of optional
    connectors. The AMP wiring is indicated as follows.....
    
    Contact #1  to +5v secondary switch
    Contact #2  to +5v primary switch
    Contact #3  to ground primary switch
    Contact #4  to ground secondary switch
    Contact #5  is common to contact #6
    Contact #6  is common to contact #5
    
    Hope this help clarify things, otherwise, I'd have your customer
    contact an AMP representative for further assistance.
    
    Bob

    
     thanks Bob,
    
     my customer use a MMJ cable provided by AMP ,but the Bypass doesnt
     work and then i don't know if
    
      _ the DEFPA board is dead
      _ THE OBR is dead
      _ the cable is dead or mis wirring
    
      now the cable seems ok, with your picture, but how can i test the
      the bypass relay or the command of bypass circuitry on the DEFPA
      board ?
    
      thanks for any ideas
    
      jean-yves

    Jean-Yves, I don't have any experience with DEFPA boards, so
    we'll have to wait for a reply from a DEFPA guru. I'm glad that
    the information I posted helped to clarify the pinout on the
    OBR unit.
    
    Bob

Hi,
	I'm not sure that this is your problem, but make sure that you have
the OBR already connected when the system is powered on.  The OBR support on 
the DEFPA (and other FDDI adapters) is not "hot-swap" capable.  The card needs
to sense the OBR at initialization to operate correctly.

	Mike P.

    
      Thanks Mike,
    
     it's a very interesting information,but could you confirm that the OBR
     command works on DEFPA board ?
    
      jean-yves

jean-yves,

Yes, the OBR has been tested on DEFPA.  As Mike said you must have the OBR
MMJ cable connected when you apply power to the DEFPA system.  The cable
is only detected properly when the host driver initializes the adapter.

If you disconnect the OBR MMJ from the DEFPA then the OBR will drop you
into bypass mode and there you will stay.  

So plug it in, cycle the power, don't unplug it and you should be fine.

Regards,
Chuck

    RE:  .1  - Correction concerning the pin assignment/usage...
    
        
    > pin      assignment
    > ---      ----------
    
    > 1,2      Relay drive +5v (200ma max)
    > 3,4,6    Return grounded internally
    > 5        Bypass present (must be externally grounded to pin 3,4, or 6)
    
    In the case of the DEFPA the +5V is connected to pins 1 and 2, and 
    the relays are controlled by driving pins 3 and 4 high (bypass mode)
    or low (insert mode).  This being the case, pin 5 (Bypass Present)
    should never be connetcted to pins 3 and 4.  The only correct wiring
    is for the OBR is to connect ("short") DEFPA OBR pins 5 and 6 together.
    When the DEFPA OBR pins 5 and 6 are (externally) connected together,
    via the OBR, it causes the ByPass PRESent signal to be tied to GND 
    (low), otherwise this signal will be pull high by an onboard pullup 
    resistor indicating there is no OBR.
    
    So, IF you are using a "staight" 6MP to 6MP cable, the pinout describe
    in the basenote, 1940.0, is correct.  I used some different signal 
    names which should better describe the function being performed. 
    
       DEFPA OBR            6MP to 6MP staight cable          OBR Unit
     -------------                                           -----------
     +5 Volts    1  <-----------------------------------> 6  Sec Relay + 
     +5 Volts    2  <-----------------------------------> 5  Pri Relay +
     INSERT Low  3  <-----------------------------------> 4  Pri Relay -  
     INSERT Low  4  <-----------------------------------> 3  Sec Relay -
    BP PRES Low  5  <-----------------------------------> 2  >---+   
                                                                 |
           GND   6  <-----------------------------------> 1  >---+
    
    
    RE: Last few...
    
    As Chuck said, the DEFPA's OBR circuit does work, but it should be
    connected prior to the driver being loaded. Bestcase is to attach
    OBR prior to power ON.
     
    Regards,
    Roger
         

    >So, IF you are using a "staight" 6MP to 6MP cable, the pinout describe
    >in the basenote, 1940.0, is correct.  I used some different signal
    >names which should better describe the function being performed.
         
    The only OBR units I'm familar with come with a power cable (with
    the 6-pin MJ), hard-wired at the AMP OBR end. So if one plugs
    the short MJ cable (about 3' long) coming out of the AMP OBR unit
    into the 6-pin MJ receptacle of the DEFPA, then my pinnout holds.
    Now if one is talking about including an "extension" cable between
    the OBR unit and the DEFPA, then perhaps your pinnout is also correct.
    Then again, perhaps the newer AMP OBR units have a removable MJ-MJ
    cable, or don;t come with a cable at all. I'm only familiar with the
    OBR's we've had and bought in recent years from AMP Inc. which came
    with the AMP bulletin I quoted from in my pinnout description.
    Your description of the functional connections (pri & sec relay etc.)
    are correct though Roger, and I will agree there.
    
    Bob

 Bob , Roger,


  thanks for your help and explanation, now i'll retest on site
  with the correct wiring

  jean-yves

                   
    Hi Bob,
    
    Your pinouts are correct for pigtail versions.  It was only the 
    reference you made to connecting the ByPass Pres signal to pins 
    3 and/or 4 of the connector I didn't agree with.
    
    The pinout I showed was based upon  .0 saying that he was using
    a "staight" cable and the OBR vendor's pinout.  Actually the cable
    must reverse the pinout for the DEFPA to work with the pinout in .0,
    as shown in .7.
    
    Normally, with a flat style cable, reversing is automatic unless you 
    intentionally rotate one of the ends (plugs).  This may lead to some
    confusion when someone says "staight", when dealing with "flat" cables.
    
    In the figure, using a flat cable with no twist, the results at the
    jacks is pin 1 connects to pin 6, 2 to 5, and etc...  This to me is
    "standard" (again, for flat cables) and if the vendor's OBR contains
    a JACK, then the pinout in .0 makes sense, allowing you to use a
    "standard" flat cable. 
    
                             Pin 1 to Pin 6
  +--------+      ------  (Flat Cable - No Twist)  ------      +--------+
  | 654321 |     | 6    |                         |    1 |     | 654321 |
  |        |     |      |=========================|      |     |        |
  +--+  +--|    [__-----+                         +-----__]    +--+  +--+
     |__|          \____                           ____/          |__|
    
     Jack          Plug                             Plug          JACK