Solved

Serial Port Programming

Posted on 2002-04-21
6
330 Views
Last Modified: 2013-11-15
I have a few questions about programming serial port devices.

1.) I have 2 serial ports on the back of my computer. I need to have more than 2 devices attached to the back of my computer. Can I use splitters to connect more devices to these ports, or do I have to install a PCI card to get more ports. Also, how many serial ports can my computer handle (Windows)

2.) How do I address each individual device (If I have multiple ones plugged in how can I specify which one I want to talk to)?

3.) The devices I'm programming simply use the power from the serial port to work. They have no chips or circut boards in them. Is there a way to identify these devices?

4.) Is there a way to control how much power is sent through the serial port?

Thanks!
0
Comment
Question by:llllllllll
  • 3
  • 2
6 Comments
 
LVL 1

Expert Comment

by:lsmgms
ID: 6958978
Hi,

You have too many questions and I have not touched serial comm for a long time.  However, I try to recall whatever I can remember, and I am mistaken please correct me.

1) I do not know how your splitter woking but if it is a passive device which I think, then you will not get more port because the signal is not "addressable".  I never tried adding a new I/O card, I think it can work but be aware the IRQ is shared among COM1/3 and COM2/4.  You can get max 4 ports.

2) Use "COM1:", "COM2:",..."COM4:"

3) The one you said is almost impossible.  It must has IC or some analog device to work with.  What are you trying to do with that device?

4) No much you can play, either:
a) If power is from RTS and DTR, then you may be able to cut half of the current, but you may have voltage drop until your device cannot work.
b) Put a resistor in between the Serial Comm and the device.

Regards
0
 
LVL 49

Accepted Solution

by:
DanRollins earned 100 total points
ID: 6959224
>> 1.) ... Can I use splitters to connect more devices to
>> these ports, or do I have to install a PCI card to get more ports.
NO, not for any type of normal serial port access.

>> how many serial ports can my computer handle (Windows)
At least 9, without doing any special device driver coding.

>> 2.) How do I address each individual device...
The device names are COM1,... COM9

>> 3.) The devices I'm programming simply use the power from
>> the serial port to work. They have no chips
>> or circut boards in them. Is there a way to identify these devices?
The device names are COM1,... COM9

>> 4.) Is there a way to control how much power is sent
>> through the serial port?
No.  I don't believe that you are supposed to draw power from the serial port.

-- Dan
0
 

Author Comment

by:llllllllll
ID: 6961482
ok, thanks. Just curious: If I only have 2 ports and I can't use splitters or PCI cards, how will I add more ports?
0
The Eight Noble Truths of Backup and Recovery

How can IT departments tackle the challenges of a Big Data world? This white paper provides a roadmap to success and helps companies ensure that all their data is safe and secure, no matter if it resides on-premise with physical or virtual machines or in the cloud.

 
LVL 49

Expert Comment

by:DanRollins
ID: 6961501
You *can* add PCI cards that provide additional COM ports, but you can't use a splitter and expect any type of normal operation.

-- Dan
0
 

Author Comment

by:llllllllll
ID: 6961539
ok thanks for the clarification
0
 

Author Comment

by:llllllllll
ID: 6961541
thank you, I got scared when I heard that I could only use 4 ports (comment before your's)
0

Featured Post

U.S. Department of Agriculture and Acronis Access

With the new era of mobile computing, smartphones and tablets, wireless communications and cloud services, the USDA sought to take advantage of a mobilized workforce and the blurring lines between personal and corporate computing resources.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

If your app took Google’s lash recently, here are the 5 most likely reasons.
Skype is a P2P (Peer to Peer) instant messaging and VOIP (Voice over IP) service – as well as a whole lot more.
The goal of the video will be to teach the user the difference and consequence of passing data by value vs passing data by reference in C++. An example of passing data by value as well as an example of passing data by reference will be be given. Bot…
The viewer will be introduced to the technique of using vectors in C++. The video will cover how to define a vector, store values in the vector and retrieve data from the values stored in the vector.

856 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question