What is it Good For?
As you probably already know, almost every serial device comes with its own proprietary communication software, optimized to its needs. The same is true also for the Device Server -- it comes with the Device Server Toolkit, ordinarily used to communicate with it. This, then, begs the question: What do we need HyperTerminal for?
Well, the answer is quite simple: Testing. HyperTerminal's strength lies in its simple interface. You just type your commands in, and watch the raw output on the screen. There aren't any buttons to click, or actions which are done without the user knowing it. This is very close to 'raw' communication -- just your input and the device's output, with no software to interpret it in the middle.
This lets you answer very quickly questions such as "what happens when I send..." -- and this, in turn, helps in the development of applications which will communicate with the Device Server directly. Before writing a whole routine in Visual Basic or another language just to send a specific command to the device, you can first send the command yourself, manually, and see what happens in real-time. Then you'll be able to write your code in full confidence that you're doing the correct thing.
Another common use for HyperTerminal is troubleshooting . HyperTerminal accesses the serial port in a very standard way. This means that it can be used when the proprietary application software for the serial device cannot open the Virtual Serial Port, or when communication fails in some other way. You can just run HyperTerminal and play with it, to see if the COM port is indeed opened, if communication reaches the other side of the line, if you get a reply, etc.
Such testing would help you decide if the problems you're having are related to software, hardware, network connectivity, etc.