Need advice on locking serial port

[Trax]

   I have written a program that reads a serial port to obtain data. The problem is that the serial port is not multi-user. Only one person can read it at any given time. I am looking for a way to "lock" the serial port when one person is reading it so that others trying to access it will know it is "busy" and wait until it frees up. Is there a "standard" way of doing this? 

[orbs]

if your program is the only one accessing the port, and only one instance of your program can use the port at any given time, then you can apply a locking mechanism like this:

NOTE: although the title mentions locking files, this method is applicable for practically any object.

 

 

[junkew]

Can you explain more. How can 1 serial port on 1 computer be used by 2 persons at the same time?

[Trax]

It is odd. I have a Lantronix Device out in Production. It is what actually connects RS232 on one side and TCP/IP on the other. So various computers can access this "virtual" serial port at the same time but the Lantronix Box will only allow one of this computer to connect at any given time.

[Nine]

1 hour ago, Trax said:

So various computers can access this "virtual" serial port at the same time but the Lantronix Box will only allow one of this computer to connect at any given time.

It is getting clearer now.  Are all those computers use the same application to access this virtual port ?  Is it written in AutoIt ?  

[junkew]

hard to say without details on device type and your environment. No details in your question so quarantee that you get vague answers

What happens if 2 users read at the same time? Why would it be a problem?

If user A reads something whats the purpose of having user B reading the device? Shouldn't all the information come together thats read from the device?

looking here https://www.lantronix.com/resources/networking-tutorials/device-servers-tutorial/ gives an idea how things can look.

developer wiki seems not to be working and their forum seems not having any acitivity

• Are all endusers on their pc starting your program from a central network location?
  • If so you could write a "lock" file in the folder when a users starts reading and you clean it when finished.
  • You could have your program start with tcp/ip udf functions to communicate with each other
  • You could make 1 PC dedicated for the communication and the other computers communicate with your central computer that dispatches

 

 

[funkey]

We have same situation. Our solution is that a service is always connected to the device and the users only connect to the service.