I want to implement a fast DAQ (10Mbit/s) system for capturing data from an array of sensors. So far I have implemented my system based on Wiznet W5300 and an FPGA and I am able to communicate through TCP/IP with my computer. FPGA working as server and PC as a client and I am using only one socket on port 5000. So far Ive tested various applications for capturing and saving the data on Windows with no success (some of them are crashing and some of them are lack in terms of speed). As I am not an expert on Network programming what would be the best way to capture and save the data on PC side as fast and reliable as possible? I am always aiming for something simple. Any type of guidance would be welcomed.
I am using tcpdump and very happy with it in linux and know that there is a Windows equivalent of it called windump. Here is the url for it :
http://www.winpcap.org/windump/
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I'm currently looking at options to allow me to build a remote COM-port solution.
The idea is to be able to access from my remote PC, another PC that's directly connected to a device locally via its serial COM-port.
I know that the obivous answer is to use a VPN between the 2 Internet connected PCs.
However, I need this solution to be as seamless to the end-user as possible.
i.e. no installing and configuring VPN software, etc.
So I was thinking that WebRTC would be great because the end-user can simply use their web-browser and not have to install any additional software.
My question is, is it possible to stream the COM port data between the 2 PCs via WebRTC?
If so, can you please point me in the right direction as to how I can go about achieving this?
Sorry if this is a ridiculous question, I'm very new to WebRTC, just exploring my options.
Thanks.
That should work great!
Networking wise you get NAT Traversal. That means the two computers can be in completely different networks, and still communicate. You may have to run a TURN server if P2P isn't possible.
Data wise you can exchange anything you want via data channels. It is datagram based and you can send/receive binary data. You get a callback telling you how much has been delivered, that way you can detect backpressure.
Are you ok with installing software on the remote host? You can do something like Pion WebRTC's data-channels. This shows you can have a browser connect to a Go process via WebRTC. Then use tarm/serial on the remote host to interact with the device.
If you want a browser on both ends there is the Web Serial API I haven't used it myself though. That locks you into only doing Chromium which might be an issue.
I've been asked to implement VPN capabilities in an existing software project on an embedded system, in order to make the device available via network to an external server while avoiding trouble with firewalls (no need for encryption, just to make it accessible).
Unfortunately, the embedded system is based on a Cortex-M4 MCU, therefore Linux, which would allow for VPN nearly out of the box, is not an option. All I've got is an RTOS and a working LwIP stack.
I've used VPNs in the past. However, my network knowledge is rather limited concerning implementing VPNs, so I'm rather stumped. As I think, I'd use the current LwIP instance for building up the tunnel connection, and the application would use a second instance for the actual network communication, while the network interface of the second instance is a virtual one (like a tap device on linux), encapsulating its low level data and tranceiving it via the tunnel connection of the first LwIP instance.
Maybe this way I'd be able to create a custom solution for the problem, but the solution should conform to any standards (as the server will be any kind of sophisticated system).
So I wonder if anyone has been confronted with a task like this, and would appreciate any hint what to do, at least a direction where to look at.
Thanks in advance!
How (GA) Global array library (an implementation of ARMCI) is used for communication between two process located on different remote machines.
Is that something similar to TCP socket programming where one process wait for data and the other transfers it ?
I try to see the documentation that ga_put() and ga_get() are two operation that used for inter-process communication. till now I only able to come up with a program running on the same machine that use shared-Memory architecture (I have used ga_put() and ga_get() to put data in Global array and to get it respectively ).
Now, I want use this program for communicating data (basically performaning one-sided communication) between two remote processes. Obiviously putting the program that I am running on single machine on the remote side will work out. It needs some way to tell which machine should we access and get the right data. And here is where I need your help. how can I do this? (what is its equivalent of TCP/IP listen, accept and connect ... on GA ? )
Or is that the case that GA also uses TCP/IP socket underneath ?
can some one please explain to me? and sample code of two remote processes communicating is also appreciable.
thanks,
I am answering my question after all. May be it will help some one looking for the same issue.
GA Library is implemented to work with MPI. So we have something like:
MPI_Init(..)
GA_Initialize()
MA_Init(..)
// .... do sothing here
GA_Terminate()
MPI_Finalize()
The answer to my question is:
MPI has the following primitives to be able to support client-server commuication:
//in the server side
MPI_Open_port()
MPI_Comm_accept()
//do MPI_Send() or MPI_Recv()
MPI_Close_port()
//client Side
MPI_Comm_connect()
//do MPI_Recv() or MPI_Send()
depending on the hardware support and the MPI implementation used, MPI might use sockets, or other mechanisms (e.g SAN (System area network)).
In general, most MPI implementations use sockets for TCP based communication.
So, yes GA also uses sockets underneath (of course depending on the MPI implementation used)
cheers,
I would like to be able to communicated with PLC controllers, so that I can send and receive custom commands on the PLC.
My idea of being able to do this was to have a TCP listener on the PLC that could read TCP incoming packets on a specific port, and execute routines based on the commands in the packets. It could also send information back via TCP/IP.
This would allow me to write software in multiple languages such as C#, PHP, JavaScript, etc. so that software can be used on any platform such as Windows, iOS, Android, etc. to issue commands to the PLC. This would also mean you do not need the PLC software (which can be costly) to view or control the PLC.
I am not a PLC programmer, so I do not know if PLC has the capability of sending and receive custom TCP packets. I would like to know that a) if it is possible b) how feasible it would be to do this and c) what exactly I should research so that I can accomplish this.
Thanks.
It sounds a bit like reinventing the wheel. You want to make something like KepServerEX?
http://www.kepware.com/kepserverex/
There are also two things to consider - one is the ability to interface with the PLC to share data (ie: for a custom HMI) and the other is to program the PLC. For the latter you still need the control software from the manufacturer unless you're willing to reverse engineer and re-write it from the ground up.
Keep in mind, also, that PLCs don't work the same way that other software does. There are no functions or procedures or classes or objects or even really any "commands", per se. A PLC is a system which executes a continuous fixed program of mostly raw logic rules and calculations. A typical interface to an HMI involves reading and writing directly to/from logic bits and word data (ie:hardware memory locations) which represent the current state of the machine. OPC already does this just fine so I'm not quite sure what you're going for.
If you're looking for a cheap/free alternative to a full commercial package, something here may work for you :
http://www.opcconnect.com/freesrv.php
If I understand correctly, when referred to "Run/Stop" you mean for the PLC to 'Start' or 'Stop' scanning the code and updating its I/O. If this is the situation, it would be perfectly suitable to add a Scan_If_On bit (which will be written by a TCP Command) in parallel connection with the "Start" bit controlled by the HMI.
This way, there will be 2 forms of "Starting" the process controlled by the PLC. HMI and TCP.
Hi Guys I'm debugging some CS program and to view the performance of the application in slow internet I tried many different ways. However the best would be the Server and the client be in the same PC ---- my debugging environments for both the server side and the client is setup in one PC.
So I'm wondering is there anyway to limit the speed? I'm using TCP but I don't know too much in-depth knowledge of it.
Thank you
There are two important factors regarding a "slow" internet connection that you need to test out since they have different implications for your application: bandwidth and latency.
If you provide some more details about what os you are running your tests on, it would be easier to recommend a way to limit the network performance.
On a related side note, it's generally a bad idea to performance test any kind of networking using the loopback device on your machine, since many aspects of this will perform very different than the regular network device on your machine.
You mention in the comments this needs to be done on windows, while the Network Emulators I know of (e.g. netem, TCN, other variants) all require Linux. So one thing you could do is create a virtual machine (VirtualBox is fine, I did similar things with it), install linux on it, configure 2 network interfaces, emulate the slow/long/lossy/jittery network between them, and route the test traffic through it from windows.
Finally I found this does what I need.
http://www.nirsoft.net/utils/socket_sniffer.html
Captures Windows Socket traffic, no matter it's local or not.