Debugging Modem Connections

Unfortunately, modem connections are harder to diagnose than anything else.

Put the word DEBUG on the M14_LINK line: 

        M14_LINK com1 tele:387-3339   DEBUG
Because of a bug in our code, add a couple of spaces from the end of the TELE number to the word DEBUG.

When the computers boot, you should see "OK" printed to the screen shortly after M14_LINK loads. If you do not see this then you may have an IRQ problem in that computer. Or it could be a baud rate problem. One way to distinguish between the two is to type: 

        echo ath1 >com2     (or com whatever)
You should hear the dial tone. If so then type: 

        echo ath0 >com2
Then it should hang up.

If this test does give you a dial tone and hangs up, then the baud rate is okay, so it must be an IRQ problem (or DEBUG is not on the M14_LINK line). You may have some other hardware using the IRQ you selected for the modem. If the dial tone does not come on, you probably have a baud rate problem. On NETCOM, try /1 or /2 (for 14.4 or faster) or /12 (for 9600) or /48 (for 2400).

If you are using COM3 or COM4, it is also possible you need to specifically state the i/o address of the COM port: 

        device=c:\lbl\utils\netcom.sys com3=3E8 int12
or 

        device=c:\lbl\utils\netcom.sys com4=2E8 int11
Once you have the drivers load okay, and are confident the IRQ is working and the baud rate is good, try to do a DIR of the remote computer. The modem should dial, and the remote modem should pick up. You should hear the modems negotiate. If you are still in debug mode you should see a CONNECT and/or CARRIER message printed to the screen. Then a reverse "M" should appear in the upper right corner of the screen.

If all this happens and you do not get the DIR:

Make sure each node knows how to reach the other. We have found this to be the most common problem. To check this, run LBL.COM on both computers. Use the right arrow key to select "Connections" and then hit . You should see both computers listed on this screen (ie, their node name). Lets say you used node numbers 1 and 2. Lets also say you are looking at the "Connections" screen on node 1. Then on the row for node 2 you should see the "Use Link Module" columns filled in with the appropriate COM port. If you are using COM1 on node 1 to connect to node 2 then the columns should say "21 COM1", or if using COM2 then it should read "22 COM2". If this information is not there then select "Enter", move to the proper row/column, type in the COM port name or module number (21, 22, 23, or 24), hit the Escape key, select "Save Defaults", and hit . Go to the other node and verify it is also setup in the same way. But remember, you are looking at the world on node 2 from its point of view so the row you need to look at is the row for node 1. This should have the COM port used by node 2 to reach node 1. What you are doing here is telling each computer what COM port to use to reach a particular node, and which node(s) are located on the other end of the cable.

However, if "DIR m:" will not dial, but, "ECHO ATDnumber >COMx" will dial, then the above problem is on the computer making the request.

If things still will not work, the best thing to do is to call a node known to be working from each computer. We will try to help. We will set up a node here and try to connect with your computers. But we must know your two node numbers, and telephone numbers for each. You will have to call us to setup a time.

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