Solved

Serial Port Programming

Posted on 2002-04-21
6
325 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
Comment Utility
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
Comment Utility
>> 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
Comment Utility
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
Highfive + Dolby Voice = No More Audio Complaints!

Poor audio quality is one of the top reasons people don’t use video conferencing. Get the crispest, clearest audio powered by Dolby Voice in every meeting. Highfive and Dolby Voice deliver the best video conferencing and audio experience for every meeting and every room.

 
LVL 49

Expert Comment

by:DanRollins
Comment Utility
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
Comment Utility
ok thanks for the clarification
0
 

Author Comment

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

Featured Post

Free Gift Card with Acronis Backup Purchase!

Backup any data in any location: local and remote systems, physical and virtual servers, private and public clouds, Macs and PCs, tablets and mobile devices, & more! For limited time only, buy any Acronis backup products and get a FREE Amazon/Best Buy gift card worth up to $200!

Join & Write a Comment

I annotated my article on ransomware somewhat extensively, but I keep adding new references and wanted to put a link to the reference library.  Despite all the reference tools I have on hand, it was not easy to find a way to do this easily. I finall…
Basic understanding on "OO- Object Orientation" is needed for designing a logical solution to solve a problem. Basic OOAD is a prerequisite for a coder to ensure that they follow the basic design of OO. This would help developers to understand the b…
Video by: Tony
This video teaches viewers how to export a project from Adobe Premiere Pro and the various file types involved.
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.

743 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

Need Help in Real-Time?

Connect with top rated Experts

12 Experts available now in Live!

Get 1:1 Help Now