How to monitor Serial COM port when a device is connected to it?

[az00024]

I am trying to develop a software that can send commands to a Radio Packet TNC (Terminal Node Controller). The TNC is connected to one of the COM ports. As there is no specific documentation available for the TNC, I am not sure about the command syntax for the TNC. In order to send the command through the TNC I am using RealTerm software. When I type in something in RealTerm and press ENTER. The command is sent through the transceiver via TNC but If I send a anything on that COM port (on which the TNC is connected) using a simple Visual Basic Program that just opens the port and sends the data on the port, I don't see any response from the TNC as well as the Transceiver as it was in case of RealTerm.

I was wondering if anyone can help me monitor the COM port while I send commands through RealTerm and see the response of the TNC as the TNC sends some packets back to the RealTerm as an acknowledgement. Is there any software that can help me do that, so that I can see what kind of data is sent along with the command to the TNC by the RealTerm?

I tried to use Virtual COM port software, where I created a virtual COM port and bridged it with the physical COM port (on which the TNC is connected) and then monitored the virtual COM port as I expected that any data going in and out of the physical COM port would be visible through the Virtual COM port, but if a device is connected to the physical COM port, the bridging doesn't work.

Can anyone help me out on this?

Thanks,

Adnan

[Jan Axelson]

Scroll down to "other tools" here for several options:

http://www.lvr.com/serport.htm#software

[HDowns]

You don't need a virtual serial port software. You need a tool like Advanced Serial Port Monitor in the Spy mode. There's a demo period, which may be enough time to do what you want to do.

[GlennP]

I have some interesting issues with Advanced Serial Port Monitor, PC resets, random characters appear, this is due to my PC being on it's way out. I have used HDD Free Serial Port Monitor with out issue for some time from
www.hddsoftware.com I believe it is free and wont time out on you!
Glenn

[DavidTurner]

Old question, but very relevant. While serial ports may be gone from consumer devices these days, it is still very much used in industrial hardware, point of sale hardware, radios, etc. In my case I was trying to capture a communications session from a configuration software tool for some hardware equipment.

In the end I found a commercial app from Eltima Software called Serial Port Monitor which did the trick for me on Windows 7 x64.
Link - http://www.eltima.com/products/serial-port-monitor/

[ruutboy]

This should be dead simple (so says the guy who has blown up more than one OS mucking around with the serial port ).

Could you post your vb code here? Just the part that converts the string and send it out. Thanks.

[Jan Axelson]

I have example code here:

http://www.janaxelson.com/serport.htm#my_example_code

[jmccabe]

If you're not using 64 bit, you can use Eterlogic's VSPE (http://www.eterlogic.com/Products.VSPE.html) and create splitters that allow multiple applications to connect to the same virtual port. I used this a fair amount and it's reasonably good but, if you're using 64 bit you need to buy it. I tried using the virtual null modem cable with VSPE, but we had some issues with it compared to Eltima VSPD.

Alternatively you could look at HHD Device Monitoring Studio which could be expensive, but can be used free of charge if you're happy to accept its limitations (I think it's got a 20min session limit, and limited features in the free version).

HTH
John