DCC Serial Port Troubleshooting / Cable Test

This is a simple procedure to test your serial connection for direct cable connect. No software other than that distributed with windows 95 is required. Please be sure both computers are correctly configured for direct cable connect.

Now put down the hammer, we are going to get this going somehow! Perhaps the most common problem with direct cable connect are the cable and port settings on the two computers. There are so many possible troubles that can fall to this feature its good to eliminate a few possibilities:
 

• The assurance your cable is correct for DCC
• The cable is plugged into the port you think it is on both computers
• Some bizare demon is not affecting DCC's ability to use the serial driver (printer, mouse, frog)
• The serial port is operating correctly
• The baud rate settings are correct and windows is using the requested values

A program that ships with windows 95 (hyperterminal) allows you to access the serial ports and modem of your computer. Characters coming in over the port are sent to your screen, and whatever you type is sent out. The starting sequence of direct cable connect is the transmission of the plain text message "CLIENT". The host computer responds "CLIENTSERVER". Until these two messages are sent/received by both computers the connection is not considered established. Its sort of like the time a modem is dialing when all of the obnoxious noises are sounding.

Note: If you have been attempting to use DCC while one or the other computer was connected to the Internet using dial-up networking. Disconnect, restart the computer that was connected, and try again. In some circumstances, DCC will fail to connect while DUN is connected to the Internet.

Disclaimer: In using this information you agree not to sue me because you or I or both are stupid. The Images and trademarks shown in this doc are copyright(c)Microsoft people.

Hyperterminal Operation

If hyperterminal is installed on your system it should be here. It is possible it has been moved to another location in the task menu.



If you did not locate hyperterminal, verify its installation into windows 95. Click START-Control Panel. Select "Add/Remove Programs" and the Windows Setup Tab. You should have a check next to Hyperterminal, if not check the box next to it and follow the directions. Do not attempt to install additional software at this time, some such as dial up networking have additional considerations.



Click on the Hyperterm ICON:



Name this connection something memorable, so if later you want to repeat the test it will be all ready to go.



Run Direct Cable Connect on THIS computer to determine the port that is being used to connect. Unless your memory is absolutely perfect please actually check by clicking "CHANGE" on the main screen. DCC will then allow you to change the Guest/Host setting (you might save some time by selecting HOST now.) Click NEXT and observe the serial port you have been using.



For example, if you are using Serial Port COM1 to connect, in the hyperterminal panel you will make the following selections:



Again, please verify the settings you are using for your serial port. They can be located in START-Control Panel-System:





Your baud rate may be different than that shown above. Note your selection and continue - Both computers must be set to the SAME BAUD RATE for DCC to operate!





Back in the Hyperterminal Phone Settings panel (Access also by File-Properties) click on the Configure Button just Below the "Connect Using" Selection box.



Note: Your Baud Rate may be different...Click OK! Hardware Handshaking MUST be selected, if not select it and restart the computer to make the change take effect. This will most likely correct your DCC serial problem.



 Now is a good time to also check the properties for the communications port you are attempting to use.  It can be found in the "Ports (COM & LPT) category. Be sure HARDWARE Handshaking is selected, also check that the absolute baud
rate is not less than the setting in the modem panel above.



Try to connect to the cable, Click Call-Connect.



Your hyperterminal should now report Connected in the lower left hand corner.



If Hyperterminal reports unable to open Com 1 {or whatever port you are using} some other application is currently using the port. It could be a printer, a mouse. Another possibility is the cable is not really connected to the port you think it is. Check the manual, or - hey just try one of the others. There usually are less than four...

Simulating a DCC Guest: (This is done on the other computer)

On the other computer, start direct cable connect as a Host. DCC should start and report

(Other Computer)

On the computer running hyperterminal, enter the String "CLIENT".


 

If you cannot type the "CLIENT" string, and hyperterminal appears to freeze up, the handshaking system is not working. The most likely cause is that the cable you are using is incorrect. It is also possible you are not connected to the port you think you are on the other (host) computer. You may try closing direct cable connect and testing the other computers port to see if it is accessable. Just repeat this procedure on the other comptuer.



You should receive an immediate response from DCC on the other computer.  If the link is working correctly, you will see a response of "CLIENTSERVER". If this happens, your cable is operating correctly and the trouble must be in some obscure part of windows. It could also be the IRQ settings, check the port troubleshooter page. It could also be some other problem listed on the FAQ page. Sometimes, the host computer (other computer) will display "Verifying user name and password..." regardless of weither the baud rate is correct, and also the hyperterminal screen will fill with garbage. If you do not see the "CLIENTSERVER" string right after what you have typed, try changing the baud rate to find out what the other computer is using because one of the two computers is not going at the same speed you have chosen to DCC at.

Note: When you change the baud rate in hyperterminal, you MUST Call-Disconnect then Call-Connect before the change takes place. It may be more convinient to set the other computer as a guest and watch for the GUEST string on hyperterminal, this is fine but keep an eye on the other computer as it will only attempt to connect about four times before giving up and you will have to click connect again.

If you can freely type characters into hyperterminal yet nothing is happening,  you can be quite sure your problem is somewhere in the port settings, cable compatability, port bios settings, or defective hardware. Try a good cable from a nice store with a return policy just to save yourself some greif. You might benefit from a null modem adapter if the cable does not work out, some strange computers do not have a normal pin-out, their configuration is reversed and the null modem adapter will cancel this problem out. You might consider purchasing an inexpensive LED RS-232 monitor all of the handshake lines will light green and you should see the TX/RX lights flash - they should cost about seven or eight loaves of rye bread or less and it can be an invaluable tool for figuring out serial  problems.
 

Related Sites

Serial Port Information Pin-outs & More

Computercraft Reference Library