Ref:  23690002
Title:  Running Diagnostics for the 3Com EtherLink (3C501) Adapter 

Date:   10/12/92

Copyright 3Com Corporation, 1992.  All rights reserved.


Before starting this procedure, make sure you have: 

    *  a loopback plug, which is a "T" connector with two 50-ohm terminating 
resistors
    
    *  a DOS startup diskette that has no network drivers on it


1.  Locate the computer that contains the board you are going to test.  

2.  Make sure the EtherLink adapter is a 3C501, by checking the 
"Assy Number" (assembly number).  It should be 1221, 0345-xx or 34-0780-xxx.

3.  Locate the adapter's BNC connector on the rear or side panel of 
the computer.  Push a loopback plug onto the round BNC connector and twist 
the sleeve clockwise one-quarter turn until it stops.

4.  Into drive A, insert a DOS startup diskette that does not have network 
drivers on it, then start up the computer.

5.  After replying to any screen prompts, remove the DOS diskette from 
drive A and insert the EtherLink Diagnostic Software diskette.
 
6a. If you have the EtherLink adapter set up for the default jumper 
configurations (I/O Base=300h, Interrupt=3, DMA=1), then enter the 
diagnostics program by typing 3C501 L at the A prompt:

     A:\> 3C501 L

"L" activates a packet test and can only be used when a loopback plug is 
attached to the adapter.

6b. If you do not have the EtherLink board set for the default 
configuration, enter the diagnostics program by typing the following at 
the A prompt:

    3C501 [L] [Ix] [Dx] [Bxxx]

For Ix, specify the Interrupt request.  For Dx, specify the DMA channel.  
For Bxxx, specify the I/O base address.  For example, if you changed the 
Interrupt  channel to 5, the DMA channel to 3, and the I/O base address to 
310, you would type:

    A> 3C501 L I5 D3 B310  <Return>


The diagnostics will check communications to the Ethernet controller by 
sending packets to and receiving packets from the adapter using the DMA 
channel.  The diagnostics also test the board's interrupt level, transmit 
and receive packets of various sizes when a loopback plug is attached to  
the board, and verify that the board receives packets that it should 
receive and rejects packets that it should reject.

Note:  The diagnostics take about two minutes to run.

If the adapter passes the tests, you'll receive the message "Your 
controller has passed tests."

If the adapter fails diagnostics, do the following:

   *  Check to make sure you have the correct adapter.
  
   *  Move the adapter to another slot. (8-bit slot if possible)
  
   *  Try a different I/O base address, interrupt, or DMA channel.
  
   *  If your computer has a Turbo option, set it to Non-Turbo or Standard.
  
   *  If tests come back with a "Loopback failure," verify the impedance 
of the terminating resistors.  It should be 50 ohms per resistor.
    
   *  Remove the adapter and try it in another 8088- or 80286-based machine. 
  
Then re-run the diagnostics as in step 6.


For more information on switches and software diagnostic settings, refer to 
your EtherLink installation guide.