COM port handling using Citect SCADA

[AliBahar]

two computers communicate with each other using DNP3 protocol based on rs232. the PC#1 acts as master and it handles data communications with citect scada. PC#2 acts as slave and it performs data communication and analysis using C++ console which is created by visual studio.
problem:I want to do opening and closing COM port of PC#1 (independent from reading&writing) using citect scada software. but I don't know how it can be done?

 

[FvM]

problem:I want to do opening and closing COM port of PC#1 (independent from reading&writing) using citect scada software.

What do you exactly want to achieve? The Scada software will open the COM port when initializing the communication. It must be free at that time and can't be used by another application as long as it's used by the scada software.

 

[AliBahar]

The Scada software will open the COM port when initializing the communication. It must be free at that time and can't be used by another application as long as it's used by the scada software.

I know that. but in DNP3 protocol the master must be able to handle link and it is not limited to data read and data write. for example suppose that slave wants to send response of previous master's req but it is not permitted because master makes the link inaccessible for slave. how it can be implemented?
I think that we never need opening port without data communicating but sometimes we need closing port arbitrarily. is n't it?

 

[FvM]

Either all actions related to the COM port are implemented in a single application, or you need to implement a driver layer that is accessed by multiple applications using the port.