Com Port Windows 7
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I recently bought an (old) laptop from someone, and despite having installed virtually no programs on it the Device Manager lists a Communications Port assigned to COM1. Attempting to use COM1 for another purpose brings up a dialogue saying that it's in use and needs to be disabled first, though even when I disable it, I have no luck getting the cable I'm working with to work on that port. What does the Communications Port on COM1 do - what is it used for? And as a bonus, how do I clear it up so that I can use COM1 for what I need to use it for?
Sep 10, 2009 Welcome to Windows 7 Forums. Our forum is dedicated to helping you find support and solutions for any problems regarding your Windows 7 PC be it Dell, HP, Acer, Asus or a custom build. We also provide an extensive Windows 7 tutorial section that covers a wide range of tips and tricks. Jul 02, 2014 Currently we have Windows 7 computers setup with our Mazak CNC machines. We have a serial cable connecting directly to a windows 7 computer and the other end of the rs232 cable plugged into the Mazak machine. In our software we use communication has ceased.
Thanks.
HashimHashim3 Answers
The cable you are trying to use is a serial-to-USB converter. You would have to install a driver for such a device. The driver would then emulate a COM port, but these devices are notoriously hard to get working right because USB ports are inherently plug-and-play, but serial ports are not (they existed long before Windows).
Comm Port Settings Windows 10
If your computer actually has a real serial port on it, then that's the COM1 you're seeing, and of course the software wouldn't be able to use it because it isn't connected to that port. The driver for the device should be emulating a COM2 or something similar.
If your computer does not have a real serial port on it, then COM1 probably is that device you're trying to use.
Either way you slice it, however, this is a problem with the software for the device not being configured correctly.
Wes SayeedWes SayeedEnsure that the COM port isn't disabled in the BIOS of your PC. You may also need to configure the COM with terminal emulation software with appropriate settings which the connected devices both use for the communication e.g. speed, parity, data, and so on.
Serial port
The Microsoft MS-DOS and Windows environments refer to serial ports as COM ports: COM1, COM2,.etc. Ports numbered greater than COM9 should be referred to using the .COM10 syntax.[12]
Additionally, you may want to look over COM (hardware interface) for another basic starting point.
COM
I/O addresses
The COM ports are interfaced by an integrated circuit such as 16550 UART. This IC has seven internal 8-bit registers which hold information and configuration data about which data is to be sent or was received, the baud rate, interrupt configuration and more. In the case of COM1, these registers can be accessed by writing to or reading from the I/O addresses 0x3F8 to 0x3FF.
If the CPU, for example, wants to send information out on COM1, it writes to I/O port 0x3F8, as this I/O port is 'connected' to the UART IC register which holds the information that is to be sent out.
The COM ports in PC-compatible are typically defined as:
- COM1: I/O port 0x3F8, IRQ 4
- COM2: I/O port 0x2F8, IRQ 3
- COM3: I/O port 0x3E8, IRQ 4
- COM4: I/O port 0x2E8, IRQ 3
What's using COM1:
As listed in the screen shot on your answer of the Device Manager, it appears that COM1 is assigned to the Communications Port.
Changing the COM1 device to use another COM port:
In Device Manager, right-click on the device using COM1 and select Properties, in the Port Settingstab select the Advanced option, and then you will see a dropdown box where COM1 is listed and you can scroll down to another COM# which is NOT in use and select it, and then clickOK on all windows until you are back to the default view of the Device Manager.
Additionally:
According to the K+DCAN USB Interface Driver Installation Manual once you install the drivers on the PC you should then find a new Virtual Comport which you will need to open the Advanced properties on within Device Manager and configure accordingly from there as per those steps or whatever you can get to work if this isn't the specific cable you have. This is the same area you can specify the COM port to use as well once you free up COM1 per the previous steps, you can then assign this one to COM1.
Not the answer you're looking for? Browse other questions tagged windows-7serial-port or ask your own question.
I'm working on software that needs to communicate with hardware over RS232 interfaces.In order to test I'm currently using 2 USB-TO-SERIAL devices connected to eachother using an RS232 cable. (Of course both USB devices are connected to the same computer).
While it's perfectly possible to test this way, I'm wondering if there is noway to create 2 virtual com ports on my system and connect them to eachother.
I'm using Windows 7 RC1
TimothyPTimothyP3 Answers
Here are a few commercial options I found after a quick search.
- Virtual Serial Port by HW group, which is free.
- Virtual Serial Port Driver by Eltima Software.
- Virtual Serial Port Kit by FabulaTech.
Add Com Port Windows 7
I am not sure if any will support Windows 7, until it is released.
Add.com Port Windows 7
Find Com Port Windows 7
I'm not sure if this will help but I checked out several months ago as a replacement for Digiboards. I haven't actually used it but it seemed that it was useful.
Virtual Com Port Windows 7
Open.com Port Windows 7
Virtual COMM Port Driver (Windows 7 - 10):