user-1: I know that Arduino nano/Uno has one Serial port to read serial data. But if I use software serial can i read more than one serial data.
I have 150 Arduino's working on a project(Can be reduced to 50 if required) these arduino will generate serial data (150 serial data as of now). I wanna connect all these 150 serial data to a computer through a single COM port. How can i make it possible. 

user14348: If each source generates messages at a low enough rate, you can put them all in series. 
Each Uno has a serial input, and a serial output, and they are all chained. Each Uno labels its message with who it's from, and passes on received messages unchanged. 
Obviously this means that if you used (say) 9600 baud, or approaching 1000 bytes per second, each device would only be able to source 6 bytes per second of message. 
If that's not fast enough for your application, then you would need a higher baud rate at the COM port.

user-1: You can attempt to connect your devices in a loop, if you are insisting on using a single serial port for each. How well all that works will depend on a lot of things.

simulate this circuit – Schematic created using CircuitLab
I have no idea what your computer is, but this is a common mention to string multiple units together where they only have a single serial port each. The software in each unit will need to pass along messages that belong to other units and you will have to device a method for achieving that process. But it can work. Message delays will exist, of course. And with from 50 to 150 units, you may find some serious frustration. But if the needs are modest, you may be able to get by with this mechanism.

-1: <p>I know that Arduino nano/Uno has one Serial port to read serial data. But if I use software serial can i read more than one serial data.</p>

<p>I have 150 Arduino's working on a project(Can be reduced to 50 if required) these arduino will generate serial data (150 serial data as of now). I wanna connect all these 150 serial data to a computer through a single COM port. How can i make it possible. </p>
 14348: <p>If each source generates messages at a low enough rate, you can put them all in series. </p>

<p>Each Uno has a serial input, and a serial output, and they are all chained. Each Uno labels its message with who it's from, and passes on received messages unchanged. </p>

<p>Obviously this means that if you used (say) 9600 baud, or approaching 1000 bytes per second, each device would only be able to source 6 bytes per second of message. </p>

<p>If that's not fast enough for your application, then you would need a higher baud rate at the COM port.</p>
 -1: <p>You can attempt to connect your devices in a loop, if you are insisting on using a single serial port for each. How well all that works will depend on a lot of things.</p>



<p><img src="https://i.stack.imgur.com/rBDFw.png" alt="schematic"></p>



<p><sup><a href="/plugins/schematics?image=http%3a%2f%2fi.stack.imgur.com%2frBDFw.png">simulate this circuit</a> &ndash; Schematic created using <a href="https://www.circuitlab.com/" rel="nofollow">CircuitLab</a></sup></p>

<p>I have no idea what your computer is, but this is a common mention to string multiple units together where they only have a single serial port each. The software in each unit will need to pass along messages that belong to other units and you will have to device a method for achieving that process. But it can work. Message delays will exist, of course. And with from 50 to 150 units, you may find some serious frustration. But if the needs are modest, you may be able to get by with this mechanism.</p>
