I'm trying to access a buttonbox to record subject responses in matlab, but I can't access the usb port or the device attached. I've tried a lot of variations of the following code. what I currently have is:
port = serial ('COM2', 'BaudRate', 19200);
handle = CMUBox('Open', 'pst', port);
I keep getting all error messages either that I'm using the wrong argument type (referring to the 3rd arg 'port' in the second line) or that no such serial port device exists (again referring to 'port').
Any ideas?
The input to CMUbox should be the port name, like 'COM2', not a port object, like the variable port. See the
CMUBox docs for more details.
PS - Make sure that "COM2" is a correct port number. Often (not always) with Windows only COM3 and higher will be valid external devices.
Related
I am creating a server socket as
% set serverSocket [socket -server accept 0]
sock005DBCC0
Since I am using the port number as zero, the operating system will allocate a free port to the server socket.
From the man page, I understand that we have to use -sockname with chan configure to get the port number.
-sockname
For client sockets (including the channels that get created when a
client connects to a server socket) this option returns a list of
three elements, the address, the host name and the port number for the
socket. If the host name cannot be computed, the second element is
identical to the address, the first element of the list.
% chan configure $serverSocket -sockname
0.0.0.0 0.0.0.0 65495 :: :: 65495
As you can see the above command returns six elements. What is the significance of :: here ? Is it referring global scope ?
My actual intention is to get the port number to which the socket is listening.
So, in order to get the port number, can I retrieve the last element of the list alone as shown below?
% set serverPort [lindex [chan configure $serverSocket -sockname] end]
65495
%
The reason why I'm asking this is because of the repetition of that port number in that list.
There are two sets of three elements in that list precisely because the server socket under the covers is actually two: one for IPv4 and one for IPv6. Tcl opens both since it doesn't know how clients are going to connect ahead of time (unless you use the -myaddr option when making the server option to make it so that only one protocol is possible). They could theoretically be on different ports, but that's really quite unlikely as Tcl tries to use the same port for both; your idea about taking the last item is probably fine.
If you really care, when you've got two addresses the first one will be the IPv4 address and the second will be the IPv6 address, so you can use lindex … 2 or lindex … 5 (or lindex … end) to pick exactly what you mean.
I'd probably do:
lassign [chan configure $serverSocket -sockname] serverAddress serverName serverPort
:: is the equivalent of 0.0.0.0, the unspecified address, for IPv6
(http://www.ietf.org/rfc/rfc3513.txt, page)
It looks like the port is 65495. You're getting two sets of three elements, one for ipv4, one for ipv6
I have a question concerning udp packets in MATLAB. I've been using the oscsend.m script to send udp packets to other applications.
http://www.mathworks.fr/matlabcentral/fileexchange/31400-send-open-sound-control-osc-messages/content/oscsend.m
It works normaly. however, now I need to make use of the pnet function from the TCP/UDP/IP Toolbox 2.0.6 http://www.mathworks.de/matlabcentral/fileexchange/345-tcpudpip-toolbox-2-0-6
because I no longer have access to the instrument control toolbox in Matlab, which oscsend makes use of.
I looked up online for answers and even contacted the authors with no luck so far. Even though the problem seems trivial I couldn't make it work.
normally the usage with the Instrument Control toolbox would be:
u = udp('127.0.0.1', 12345) %12345 being the port
fopen(u)
oscsend(u, /test, 'f', 1.05) %"f" indicating a floating number
but now without udp or fopen I tried to use pnet like this
%write data to UDP
data = [oscstr(path) types data];
sock=pnet('udpsocket',12345) %it returns 0, a sign that the socket is working
%however when I try to send the oscsend signal through this socket nothing happens
pnet(sock, 'writepacket' data) %data being the output of oscsend
I also tried with no luck integrating the pnet function to oscsend but I couldn't recieve a signal, (I am working with another instance of MATLAB which is recieving the data sent from the previoulsy mentioned port).
This is what I did inside oscsend and none of them worked
%write data to UDP
data = [oscstr(path) types data];
%pnet(u, 'writepacket', data, '127.0.0.1', 12345 );%
%pnet u 'write' data %
%pnet(u,'write',data, '127.0.0.1', 12345 )
%pnet(u,'write',data, '127.0.0.1', 12345 ) %returned value?
%pnet(0,'write',data, '127.0.0.1', 12345 ) %
%sock = pnet('udpsocket',12345 ); %
%pnet(sock,'write', data, '127.0.0.1', 12345 )
Thanks to all of you in advance who took the time to read this.
Best.
Mario.
It's not clear to me what UDP port you want to send your data to, and what sort of process you're using to monitor and test your code. There are two ports involved... One is the local port that you're binding to (that's the argument to 'udpsocket'), and the other port is the destination port of the packet, given along with the destination host.
It appears to me that the Instrument Control Toolbox syntax requires the destination hostname and port during creation. It allows you to specify the local port as an optional argument if you want to. In constrast, pnet('udpsocket') takes the local port. You should notice in your first set of code that nothing specifies the destination host, which should make you suspicious... If you read on in the UDP docs of pnet.m, you'll see that there's another function: pnet(sock, 'udpconnect', 'hostname', port), which "connects" the UDP socket to the host/port pair, so that you can leave out the hostname/port when doing writepacket.
So here is what I think the equivalent is of your original Instrument Control Toolbox code:
sock=pnet('udpsocket',1237); % Does local port matter? You haven't said...
pnet(sock, 'udpconnect', '127.0.0.1', 12345); % Destination port
pnet(sock, 'writepacket', data);
You should ALWAYS use 'writepacket' for UDP, never 'write'. And note that you can either do 'udpconnect' as I've listed above, OR you can supply hostname/port with every writepacket, as you were trying to do.
What I can't figure out from your question is how 6351 enters in, as that never showed up in your reference code.
btw, there is also oscmex, a library based on liblo that allows you to send/receive OSC messages directly from/within matlab.
Thanks to my supervisor here is the code if you ever need to send udps via oscsend.m using pnet
http://www.mathworks.fr/matlabcentral/fileexchange/31400-send-open-sound-control-osc-messages/content/oscsend.m
just add the following code at the end of oscsend.m
%write data to UDP
data = [oscstr(path) types data];
pnet(u, 'write', data)
pnet(u, 'writepacket', '127.0.0.1', 12345); %127.0.0.1 being the IP and 12345 the port
If a computer has multiple network cards, all of them connected to different networks and functioning properly, when we open a socket, how does the OS determine which NIC to use with this socket? Does the socket API allow us to explicitly specify the NIC that is to be used?
I'm writing this from a Linux perspective, but I suppose it applies everywhere.
The decision is made when the socket is bound. When bind is called, the address you specify determines the interface the socket will listen on. (Or even all interfaces.)
Even if you don't use bind, it happens implicitly when you connect. The destination is looked up in the route table, which must contain a route to the destination network. The route also contains the interface to use and can optionally even specify the source address. If no source address is specified, the primary address of the interface is taken.
You can actually use bind together with connect, to force your outgoing connection to use a specific address and port. A socket must always have these two bits of information, so even when you don't, the primary address is used and a random port are chosen.
I dont know why im included in the edit suggestion when i was not even related to this question .I got similar edit suggestion before as well..might be some bug/issue.
(If you feel inclined to up-vote, #Shtééf's answer deserves it more than mine.)
That depends on whether you are connecting or binding.
If you bind, you can bind to a specific IP address corresponding to one of the machine's interfaces, or you can bind to 0.0.0.0, in which case the socket will listen on all interfaces.
If you connect an unbound socket, then the machine's routing tables, in conjunction with the destination IP adress, will determine which interface the connection request goes out on.
It is possible to bind a socket then connect it. In this case, the socket will remain bound as per the bind call when it makes the connection. (Thanks to #RemyLebeau for pointing this out.)
I'm not really sure which method is the best, but there is an alternative theory to the bind()-before-connect() approach that Shtééf presented. It's to use setsockopt() with SO_BINDTODEVICE . See: http://codingrelic.geekhold.com/2009/10/code-snippet-sobindtodevice.html
As an alternative, you can search for the appropriate nic based on its name:
//Find the ip address based on the ethernet adapter name. On my machine the ethernet adapter is "Ethernet"
System.Net.NetworkInformation.NetworkInterface[] nics = System.Net.NetworkInformation.NetworkInterface.GetAllNetworkInterfaces();
System.Net.NetworkInformation.NetworkInterface ethernet = nics.Where(n => n.Name.Equals("Ethernet")).Single();
UnicastIPAddressInformation uniCastIPAddressInformation = ethernet.GetIPProperties().UnicastAddresses.Where(a => a.Address.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork).Single();
IPEndPoint localEndPoint = new IPEndPoint(uniCastIPAddressInformation.Address, 9000);
//Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
//Bind and start listening
listener.Bind(localEndPoint);
listener.Listen(10);
I'm writing a SIP stack, and I need to insert an ip address in the message. This address needs to be the one used for sending the message. I know the destination IP and need to determine the NIC (its address) that will be used to send the message....
To expand a bit on Remy Lebeau's comment, GetBestInterfaceEx() is your best bet, if you're on Windows XP or newer. That will work for both IPv4 and IPv6 addresses.
GetBestInterface/GetBestInterfaceEx return the index (call it IDX) of the most appropriate interface to use to contact some address.
Then you can map that index into a local IP address by getting your interface<->IP address mapping using GetIpAddrTable or GetAdaptersAddresses if you're dual-stacking (supporting both IPv6 and IPv4).
Iterate over that table and find the interface with the dwIndex (or IfIndex, in the case of GetAdaptersAddresses) matching IDX.
It's usually best to allow the IP address your SIP stack will operate on to be set as an adjustable configuration option. It means the user will need to set a configuration option but at least your stack will know the IP address it's operating on.
If that's not feasible then an approach you could use is to send out the SIP request on all IP addresses using a dummy value in the Via header such as 0.0.0.0 and set the interface you get a response back on as the default one. This approach alos as the advantage that the SIP response will tell you the public IP address the request was received from which can be useful if your SIP stack is behind a NAT.
Over TCP, I think you can get the address of the local side of the socket after connect(). I don't know if the same is true for UDP (I suspect not), but it might be worth a try.
The socket will allow you to Bind to a local endpoint before calling connect (both UDP and TCP).
That is all ok if you know the port. However, if you want the port to be ephemeral (e.g. some random port number) then you must come up with your own algorithm to do so and robust code to handle the cases where the port is exclusivly taken by another application.
I am writing a UDP test client/server and i want to get it through firewall. Supposedly all i need to do is have both sides send to the correct IP and server. Getting an IP is not a problem but how do i have the client pick a random free port and report it to the user? I eventually would want it to connect to a matchmaker server but right now i need a simple working prototype and i would like to cout the port number so my friend/tester can send me the # via IM so we can test.
How do i get the port number?
sorry for the long desc. I notice people tell me not to do what i am asking when i dont give a desc :(
To use the highly technical term, this is actually a pretty icky problem or even a pair of icky problems. Depending on the configuration of the firewall, it will usually allow responses from another endpoint on the IP endpoint as the request came from. So... if you friend receives the UDP datagram using something like the recvfrom() system call, the address parameter will receive the IP endpoint information to respond to. So the other end should be able to respond with a sendto() using the same addressing information. Something like:
/* initiator */
struct sockaddr_in hisaddr;
memset(&hisaddr, 0, sizeof(hisaddr));
hisaddr.sin_addr.s_addr = htonl(target_ip);
hisaddr.sin_port = htons(target_port);
sendto(sd, msg_ptr, msg_sz, 0, (struct sockaddr*)&hisaddr, sizeof(hisaddr));
/* receiver */
struct sockaddr_in peeraddr;
socklen_t peer_sz = sizeof(peeraddr);
recvfrom(sd, buf_ptr, buf_sz, 0, (struct sockaddr*)&peeraddr, &peer_sz);
/* build response */
sendto(sd, msg_ptr, msg_sz, 0, (struct sockaddr*)&peeraddr, peer_sz);
The peeraddr on the other side will be your external address or, more correctly, the IP address of your firewall and the port number that it chose to use. The port number that you specify in your code may be completely different than the port that your friend would have to send data to. Ultimately, it might not matter what port you choose to use since the firewall might be sending and receiving on an entirely different port - this is what Network Address Translation is all about. I would recommend reading RFC3235 for some tips on how to overcome that hurdle.
The best approach IMHO is to:
Let the OS choose a port by either calling bind() with a zero port number or skipping the bind altogether
Having the client receive the address information from the socket layer (e.g., the fifth and sixth arguments to recvfrom())
The client sends response to the endpoint retrieved in the previous step
Tweak the firewall configurations until the previous steps work
Of course, all of the magic is in the last step. If you can disable NAT or ensure that the firewall is never going to switch ports, then nailing down a port number and bind-ing to it will work as well. You might want to take a look at %WINDIR%\system32\drivers\etc\services (or /etc/services depending on your OS inclination) to get an idea of what port numbers are reserved or generally in use.
bind() the socket before you send your data. Specify port 0 to bind(), and the OS will pick an unused port for you. You can then use getsockname() to find out what port wsa chosen.
Generally speaking - you - as the developer - choose the port. You can set your application to read the port from a config file or user input - but no magic firewall is going to tell you what port to use...
If I'm understanding your question correctly, I'm not sure there's a way to do what you want programatically (and even if there is, I don't think it's the right approach). I think you need to find a port that isn't in use on the server machine (and perhaps a different or the same port on the client machine, if communication is bi-directional) AND that port must be able to pass through your firewall. I assume since you say "getting an IP is not a problem", you've already configured your firewall to forward some or all ports to a specific computer inside the firewall? If so, the port you seek is one of the ones you forwarded. You can just pick an arbitrary one, as long as no other service is running on that port. Ports below 1024 are reserved, so you probably want to pick a higher number than that. You can use a simple portscanning tool such as nmap to see which services are running on your computer on which ports and pick a different one. Note that nmap can be fooled by firewalls and various bind rules when sockets are created.
I think you're better off picking a fixed port rather than relying on the random port number chosen by the O/S.
If you use a random port you'd have to change your firewall settings each and every time you run the program.
If you're using WINSOCK check this link:
http://msdn.microsoft.com/en-us/library/aa280717(VS.60).aspx
Basically you have 2 choices set the port to 0 and let the system assign you one or chose a random one try to open the socket if it doesn't work try another (be sure to steer clear of reserved ports)