I want to design a webform that user should fill some fields. The value of one field should be read from Serial port (COM1) of client computer which a special hardware is connected to it and the user presses the Send to PC key of the hardware when filling the form.
How i can listen to COM1 port in my webpage and get the value of COM1 and place it in the web form automatically?
I heard that ActiveX controls can do this but it is compatible only with IE (right?). The other option is Java applets.
I want a simple solution which be compatible with (at least) IE/Firefox/Opera.
I the server-side i can have ASP or PHP but i am appreciate if you give a solution for each.
UPDATE:
We can tell clients to change their security settings to accept our ActiveX/applet.
It is also possible for us to tell clients to install a custom program which runs as a service and reads from Serial port.
The problem is the read data should be entered to the webform automatically and immediately.
The java applet is a good idea, but the client have to install JRE which is large in size.
Is there any other option?
With a Java Applet you can read from the serial port but you need to sign the applet for security reasons. To firm unofficially (no sun's firm) you have to create a certificate. Here is an example.
I was solving the same problem and I did it. It is done using a Java Web Applet. You will need NetBeans. Read "readme" first. Let me know if anything, pls.
http://racky.wz.cz/applet_rs232.zip
Designed for serial COM1. Plug in it a RS-232 cable and short (connect) pins 2 and 3 on the other end.
This would appear to break most security models for the web. I cannot think of a way that it would be possible to do within a browser without granting an applet or ActiveX control a whole lot of permissions (and even then I'm not certain it's possible). I think it's likely to require some kind of native "thick" client-side application to do the communication with the serial port.
Java might very well be your best choice for maintaining cross-browser and cross-platform compatibility. A quick search brought up these pages that you may find useful:
The server-side choice doesn't matter at all. Once the client reads the data, it's the same as sending any other data to a server-side script.
来源：https://stackoverflow.com/questions/3310643/how-to-read-from-serial-port-in-a-webpage