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Using Hyperterminal to test null modem cable

Posted on 2002-06-05
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Last Modified: 2013-12-27
I have a null modem cable connected to serial port of a laptop and going to serial port of NT server.  I open hyperterminal on both machines and need to test connectivity of the two comm ports from laptop to server to verify they are able to communicate with each other.  I am not familiar with use of hyperterminal.  When I type in it no characters appear on either one.  They both say they are connected and the lights on the null modem are all lit green, so i assume the cable is correct.  In  order to test connectivity shen I type characters in laptops hyperterminal shouldnt I see them on the servers hyperterminal program.  ANy ideas what I am doing wrong or if I am even doing this correctly.
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Question by:Janice1967
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8 Comments
 
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Expert Comment

by:Banyan99
ID: 7059654
This should work. Double check and make sure you have the all of the settings set the same (baud rate, stop bits etc...).
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by:Janice1967
ID: 7061981
All the settings are the same baud rate, stop bits,etc.  I noticed although the IRQ and I/O for the serial port I am using in control Panel/ports is different than the IRQ/I/O that it says in the BIOS.  Is this ok.  should I change it in control panel so it is the same as BIOS.  For example, On my nt server for serail port 2 it says 2F8, IRQ line 3.
For Port 2 in control panel/ports configuration is 2F8, IRQ 15.  IRQ's are different.
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LVL 17

Expert Comment

by:mikecr
ID: 7090259
Sounds an awful lot like the modem speed has not been negotiated properly. Try setting the connection speed in Hyperterminal in the properties of the connection to 19200 and the same to the other computer and see what happens when you connect.
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by:rid
ID: 7090396
I think serial communication leans rather heavily on interrupts. IRQ15 is often used for the secondary IDE controller. It may be a good idea to try and resolve this confusion about the IRQ:s. 2F8, IRQ3 sounds "normal" for COM2 in a standard PC.

Is the purpose of this exercise to test the cable or are you building a communications link? For HW testing purposes it may be easier to use a more primitive O/S, like DOS...

Cheers
/RID
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by:Chicko
ID: 7133501
Simple trick!!!!

unplug the cable from the NT box, get a bit of solder or thin wire, and join pins 2 and 3 on the cable. Then type stuff into hyper terminal on the laptop. it should repeat everything you type.

try the same thing from the NT box. If both work then there is something wrong with the cable or differences between the setups.

check out http://www.hardwarebook.net/cable/index.html for the exact cable connections. mayby the cts or dtr pins are not connected correctly?

good luck, regards Chicko
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by:Asta Cu
ID: 7150624
Still open today, do you still need help?

If an Expert here helped you resolve this, please convert their comment to the Accepted Answer to grade and close this.  If more is needed, please provide an udpate.

Expert input with closing recommendations not only welcome but most appreciated so we can bring this to a conclusion if Asker doesn't give us an update here.

Thanks a lot,
":0) Asta
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by:Janice1967
ID: 8379897
I resolved this by setting the com ports interrupt, I/O to be the same as the BIOS setup.  Now everything works.
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ID: 8402849
PAQ'd & points refunded

Chmod
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