I made a Delphi application that transmits data to COM port every second. The COM port is a virtual null-modem (com0com) between the data transmitting software and a VirtualBox machine. Everything is fine, but if nothing is listeninig at the other end Host Windows becomes increasingly unresponsive.
After I went from com0com to pure hardware solution the problem disappeared. Also my application in virtual machine stopped to hang regularly.
Related
On our team we have a standardized development setup where we have a Win8 workstation with various VMs running on Hyper-V. All development takes place on a VM.
I was having an issue where I couldn't check out a project from a Team Foundation Server using VS2012, it would start checking out, but then the connection drops. I fired up Wireshark to check what's happening, but then it worked fine. I double checked:
When Wireshark(or rather WinPcap which is doing the actual capture), running on the workstation, is capturing packets from the VM's virtual NIC, everything works fine.
As soon as I stop the capture, TFS can't check out.
So I can't even properly inspect the network traffic to diagnose the issue, because the act of inspecting traffic changes it. Heisenberg would be proud!
I thought it might be an issue with Wireshark overriding some check-sum offloading settings, but it seems not to be the case.
So what else can be affected by running Wireshark? I rather thought that the point of packet sniffers is that they don't change the packets as they capture them.
That means you are picking traffic that normally would not be picked by the vmnic.
Try to check on mac address level what is happening. Maybe mac address conflict between VMs ?
ps. You can whireshark without promiscuous mode. The the Heisenberg rule should not apply :)
I wrote a multi-tier application suite in Delphi XE, using DataSnap (VCL application).
This will be used internally, in my company, mostly to replace the outdated fax communication.
Everything works fine, but I came across an unpleasant situation: The server machine is behind a router, so it has an internal network IP. I forwarded (in the router) all incoming connections on port 211(DataSnap default) to the server's internal IP and about 8 times out of ten all the clients connect to the server without any problems.
The problem is that for the rest 2 times I get all sort of connection errors (mostly connection timed out). When it does this I have to close and reopen either the server application either (some of) the clients, and then it works.
Right now I'm still in the design phase, so it's only a bother, but when I do release it I don't want either to tell everyone NOT to EVER close the application (once it works, it works, no more problems), either close and reopen the applications each time there is a connection problem.
How can I eliminate this problem?
I had (only) a look at NetCat and SoCat, but (to me) it seems overkill for this situation. Is there another way to solve this?
The solution was switching off router's internal firewall.
I'm using Delphi to develop real-time control software and over the last couple of years I have done some work running older Windows installations under Microsoft's VirtualPC and it works fine for 'pure software' development (i.e no or limited access to the outside world). Such tools seem able to work with network connections but I have to maintain software which performs I/O via the parallel port (via a device driver). We also use USB I/O. In the past I've liked Microsoft's virtual tools because it takes time to install a new operating system and then (in my case) install Delphi and a load of libraries and components to provide development support. In these circumstances I've not been too bothered by my lack of access to the low-level I/O ports.
I want to up my game and I'm happy to pay for a good virtualisation tool IF I can have access from it to the outside world, i.e I want to be able to configure it to allow access to my machine's parallel port and com ports in the same way as if it was running natively. This access has to be able to expose the parallel port in register terms, i.e to 'see' the port at address $03f8 for example and to support I/O operations of those registers (via the appropriate kernel access) as my Windows 7 64-bit installation is able to do.
I see that there are a number of virtualisation solution out there now but it's quite hard to acertain the capability of each at such a low level. Does anyone have any experience or knowledge in this area?
The VMware products would be suited best for this. You can add virtual serial and parallel ports and forward them to a physical port on the host, or even to a file or a named pipe.
You can also connect any USB device that is connected to the host machine.
This works with VMware Workstation, but might even work with the free VMware player too.
I have a Delphi application that reads/writes to a COM port connected to a large hardware device, so I don't usually have the hardware available during development. That said, the communication protocol is fairly simple, so I can generally do the development and have someone onsite test it, and it usually works. Occasionally I run into a harder problem, though. To solve this, I'd like to setup a virtual COM port where one side of the COM port is my application and the other side is a very simple COM port debug console (similar to the old modem terminal programs), where ASCII commands my app sends are logged onscreen and I can type in some ASCII command to send back to my application to simulate the hardware device. I've been unable to find any tools that provide a virtual/software COM port and a console/terminal to debug with. Does anyone have software suggestions and steps to set something like this up?
The software/virtual COM port and terminal need to support Windows 7 64-bit (or Vista 32 if necessary).
I'm doing something similar with paired virtual COM ports created by
http://com0com.sourceforge.net/
I'm using Advanced Virtual COM Port and I'm quite happy with it. Not free, but works like a charm - even with Win7-x64.
Can't you just insert a redirector at the lowest level of your application which will pop up a console instead of writing data to COM? Should not take long.
I can't vouch for it, but sounds like something like this is what you're looking for. http://www.windows7download.com/win7-free-virtual-serial-ports-emulator/yarqmowu.html
I have used Eterlogic's Virtual Serial Ports Emulator successfully for exactly this on a laptop with no serial ports. It's a bit easier to set up than Com0Com, which I have also used. It's also useful for serial port spying if you need to reverse engineer any communications
The 32-bit version is free, the 64-bit version is currently $25. Try it out on Vista32 to see if it does what you need.
I use Com0Com for this purpose, but I don't know whether it works with anything more recent than Windows XP.
I am connecting to a SQL Server Express 2005 on another PC on our company LAN.
On my PC (which has Windows7) the connection is immediate. On our tester PC (who has Windows XP), the connection takes about 5 to 6 seconds every time. This is the same network and the same server.
I am not talking about a connection through an application, but also through the control panel or anything else.
Any suggestion where this time difference may be coming from, what setup option might be involved or how we can speed up the connection on the XP PC?
Is the XP computer using an IPv4 address while you and the server are using IPv6? Could be an issue with the routers/switches along the way.