Clearing TCP Connections

Hi,
Is there a WAAS command that will allow me to clear a TCP connection thats been hung for 500+ hours? The WAE is running 4.0.13.b23.
Thanks,
Mike

Thanks Zach,
The app (the only app I've had issue with) in question is a home grown product and I'm not quite sure whats causing the WAE to keep connections so long. I've check asymetric routing etc...but traffic is routing correclty. I think it's an app issue but the developers here don't like it when I say that:) My local SE and CCIE worked on this alittle last week in there lab but I had to finally remove the client and server from my WCCP ACL at the central location. Once I did that it removed the hung connections at the remote WAE (it's inline at the site) but when I logged into the 7300 at the central location I noticed they never cleared on that device. It's not building any new connections just hanging onto the old....for instance some have been open for 1000+ hours. I just don't want to force a reboot to get them cleared but it looks like my only option.
Mike

Similar Messages

I sometimes get Error 42 when opening a TCP connection - how can I fix this ?

In my Labview application I am opening a TCP connection in an identical way to the Data Client example. I am using a direct connection to external equipment using an ethernet crossover cable. The error occurs on at least 2 different PCs.
The error can occur regardless of whether anything is connected to the ethernet port of the PC.
The only way I have found to clear the error is to power down the PC and restart with a connection to the office LAN. Then I can swap back to the crossover cable and talk to the remote equipment once again, ...unitl the next time the error occurs.
I have LabView 6.0 running on Win98.
Any help greatly appreciated.

Jeremy,
Thanks for taking the time to answer
I already checked the link you suggested but I am connecting to my remote instrument with a 2m cross-over cable.
I Have looked into this a little further, it seems the sequence of events is as follows -
1. After some hours the connection gets lost.
2. TCP Read returns error 66 - Connection was closed by peer.
3. If I try to restart my program I get Error 42 at TCP open Connection.
4. Rebooting the PC doesn't clear the error 42 problem.
5. If I try to PING my instument I get "Host unreachable".
6. I have to "refresh" my network card by connecting to our LAN and either opening a file on another PC or simply sending a PING to another PC.
6. I can then reconnect my remote instrument via cross-over cable
and we're up and running for another few hours.
I get the same problem on two different PCs with different NICs and different OS (Win98 and WinME)
I am assuming that because a reboot has no effect that its not a memory allocation problem.
It seems like LabView stops talking to the NIC and then gets locked out some how.
Any other tips ?

TCP connect consumes 80% of CPU load

Hello!
I've done some profiling on a Java application and i see that 80% of the time the application has on the CPU is used for establishing a TCP connection.
Socket c;
c.connect("",xxxx);The application performes several hundreds of connect per minute, but most of them take about 5 sec or less, but som uses the CPU for more than 130 seconds!!
Could, i suspect it too be a problem with the network card beeing overloaded and will try wit multiple NIC's. But does anybody have any experience with this??? and maybe point out some improvements.

Hello!
Should have mentioned it.. we are using a
ThreadPoolExecutor with 1000 threads in the core. But
shall look into that. thanx :-)
There may be some improvements that can be done in
that areaThis doesn't have anything to do with what I am talking about. I am talking about a pool of open connections (sockets) not a pool of working threads.
Here is the thing when you (in a program) tell a socket to close the OS gets told that the socket is no longer in use and should be closed. The OS then closes the socket but doesn't actually release the allocated resources until it feels like it. It feels like it when it (a) has some spare time with nothing else to do or (b) it has to reclaim the resources because something else needs them.
In short the OS final clean up of socket resources is rather akin to garbage collection by the JVM... it will happen but not neccessarily right away and you really can't do anything about that.
Let me make this 100% clear. This is NOT a Java problem. This is an OS "problem". Although it's not really a problem either. Under most sensible scenarios that model works just fine... your problem is that you are doing something foolish.
Creating and disposing of sockets is an intensive task for the OS. The queue of sockets waiting to be finally disposed of by the OS grows and grows while it is busy creating new sockets for you until eventually it HAS to clean up in order to give you a new socket. Then you pay a big penalty in time while the OS does it's garbage collection.
So in summary as it goes this situation is insolvable. What you need to do is not be creating and destroying hundreds of sockets every second. How can you do this? By using a pool of already open sockets that are shared among your various threads.

Reconnect TCP connection

Hi,
Is there a way to have a passive TCP communicator open and constanly running and use an active one that connects, disconects, and then automatically reconnects periodically? I'm using the active TCP vi as a sub vi to send commands to another computer but I need to send all the commands seperately. Also, the main vi does other stuff in between those commands, so I can't just leave the active connection open. There is an example vi called "reconnect TCP connection", but I can't open it because it is for labview version 7.1 and I'm using labview 8.5. I don't know if it would even do what I want, but if anyone knows how to get around the old version problem (or locations on examples for labview 8.5), please let me know. Any help/ideas would be amazing, Thanks!

It depends on how far apart the packets are. If they are going to be
sent pretty regularly, you can just put a TCP Read in your main loop
with a timeout of maybe 100 ms. If nothing comes in that 100 ms, clear
the error (56) and process your other code. If the packets are not sent
very regularly and you don't want to wait every iteration of your main
loop listening for 100 ms, you can use a Producer/Consumer pattern with
the producer has a wait on listener, and when it receives information,
puts it in a queue for the consumer loop (which will run the bulk of
your program). I modified the template of producer consumer to give you
an idea how to work it. Problem with this method is it's difficult to
communicate back to the producer loop (for example, of you quit the
program from the consumer, the producer will continue to run and the VI
won't stop.) This may be a rare example of where it's ok to use local
variables.
Attachments:
ProducerConsumerDatawithTCP.vi ‏29 KB

Excessive Port 80 TCP Connections? How many connections are normal?

Hi. I'm running MacOS X 10.3.9 on a Mac Powerbook (with all of Apple's latest Security Updates installed. It is a virgin installation and no other software programs have been installed). I then installed Norton Personal Firewall 3.0.2 in order to monitor all my ports.
By default, Norton Personal Firewall (NPF) is not set to log the number of outgoing connections for port 80, although port 80 is the port typically used by most web browsers to contact other sites on the web. If you disable port 80, then your browser will not be able to function or access the web. Therefore it is mandatory that you leave that port open. But what if some unknown hacker wrote a Trojan program to specifically ferry information out of your computer and back to him using that port, then there'd be no way to stop it once the Trojan was in place. If you disabled the port to prevent it, then you'd also disable yourself from the web. If you opened the port for your browser, then the trojan would have free and open access. At least that is the theory that has me wondering about the seemingly high number of outgoing port 80 connections displayed in my NPF logging window. Therefore, I'd very much like to find out if other users who are running a version of Panther with NPF are experiencing the same high connections behavior on port 80.
To create the scenario for this behavior, basically you just open your NPF panel and enable all logging for port 80 (by default it is disabled). For those of you who don't specifically know how to do this, the following is the directions . . .
. . . Open your NPF Service Settings pane. From this pane, highlight the service called Web Sharing Port 80. Click the Edit button at the bottom of the selection window. A new pane will then show the controls named Ports, Logging, and Notification. Bring forward the Logging controls and enable both checkboxes for Allowed and Denied for the Outgoing direction. Click Save and close the window.
Once the above is done, close all other windows and open your NPF Logging window on your desktop and keep it visible for you to look at. Clear all existing entries in the log so you'll start with a clean slate. With everything set up and a web connection available, open your Safari browser (or any browser) to an online web site. On my computer, my Safari bowser is set to open to Apple's website - www.apple.com. Once the browser is open, Apple's website is then displayed.
The result . . . surprisingly, after only a few seconds, a HUGE number of port 80 TCP connections to that website address start to show up and flow into my log. In a matter of only 3 or 4 seconds, at least 250 separate TCP connection entries will show up in my log, and they all have the same web address. If I then click on anything on the page or surf to any other website, the log entries will change to the new site address and start up again, and in some cases, in a matter of less than a minute the number of entries can easily reach into the thousands. I've seen 20,000 entries or more flow into my log after a couple of minutes. And the only way to stop the madness and the entries is to disconnect from the web. Those many entries and this behavior does not seem normal to me, no matter what port is selected and no matter what log settings are enabled. A dozen to 15 or 20 entries for a given site I can understand (I've been told some browsers can open at least 10 connections at a time), but hundreds to thousands, I cannot. I can't understand why any program under any circumstance would need to generate those many log entries in such a short time frame. My problem is I have nothing to compare this data to, I only have my suspicions and have no way of knowing whether this behavior is normal or not. So I am asking for others to make a comparison on their computer if you are running any version of Panther and Norton Personal Firewall and give me your results so I can determine what is normal or not. I've heard of certain hacker attacks called TCP flooding and other forms of attacks, and I don't want my computer to have been secretly taken over by a hacker or the initiator of such attacks unknowingly. Furthermore, this is not anything an average user would even normally notice, simply because Port 80 logging is not usually enabled in NPF. Nevertheless, I need to find out the root of this problem and learn whether this is normal. Other than these high number of connection entries, my web surfing seems normal and I haven't yet experienced any seeming sluggishness accessing sites. Any help anyone can offer I would appreciate. Thanks to everyone in advance.
Here are some images of my own settings and results:
http://homepage.mac.com/starshone/misc/Port80Settings.jpg
http://homepage.mac.com/starshone/misc/Port80Log.jpg
Mac OS X (10.3.9)

But all those connections are how the web works. Each HTML page has dozens or more links. Each graphic or other page element is a new HTTP request on port 80 back to the originating server (or another server even). So it's normal to have a lot of port 80 connections going out if you surf the web.
You can see the individual elements that make up a page in Safari by going to the "Window" menu and showing the "Activity" window. I see CNN's web site tonight has 113 items on its home page. Apple's is 41. My home page is 10. So it's easy to get a lot of connections.
Some applications also use port 80 to check for updates, so you might see the occasional port 80 connection even when you're not surfing the web. These are also nothing to worry about.
charlie

Tcp connection to Processing not working

Hello,
I had a processing code designed for me to generate 8 different types of an audio signal - labeled as 8 conditions for an experiment i am running. I can use processing and Supercollider to play the audio signals no problem but when I try to set up an TCP connection between Processing and labview (2009 version) to run my experiment it does not execute the commands that have already been embedded into the processing code. I am using the correct port and IP address, as specified in the processing code but for some reason the commands that I set in labview, to generate the audio condition, do not work.
I can provide the audio code if necessary. When I 'run' the TCP connection in labview no errors are reported so it is making a connection but for some reason the command (e.g. 'C1' for condition 1) does not execute and I hear no audio.
any help would be greatly appreciated,

Apologies i may not have been clear before. The processing software is listening for a connection from labview. I am using the TCP connection to send a command (i.e. 'C1') to processing so that it will be executed. The reason I am using the TCP connection is because for my experiment I require subjects to follow this audio signal which is connected to the DAQ. I am basically assessing how well subjects can follow the signals. Labview allows me to run the experiment and all its elements at once.
I have sample labview work that I am basing everything on which I am told worked fine before but for some reason when i replicate their labview work it doesn't seem to work for me.
Attached is the 'labview connection patch' code that I run in 'Processing'. This code basically listens at a particular port/Ip address for a connection/command
Attachments:
labview connection patch.docx ‏95 KB

ASA 5505:Static Routing and Deny TCP connection because of bad flag

Hi Everybody,
I have a problem. I made a VPN site-2-site with 2 ASA 5505. The VPN works great. And I create a redondant link if the VPN failed.
In fact, I use Dual ISP with route tracking. If the VPN fails, the default route change to an ISDN router, situated on the inside interface.
When I simulated a VPN fail, the ASAs routes switch automatically on backup ISDN routers. If I ping elements, it works great. But when i try TCP connection like telnet, the ASAs deny connections:
%PIX|ASA-6-106015: Deny TCP (no connection) from 172.16.10.57/35066 to 172.16.18.1/23 flags tcp_flags on interface interface_name.
the security appliance discarded a TCP packet that has no associated connection in the security appliance connection table. The security appliance looks for a SYN flag in the packet, which indicates a request to establish a new connection. If the SYN flag is not set, and there is not an existing connection, the security appliance discards the packet.
thanks!
EDIT: On the schema, The interface of the main asa is 172.16.18.148...

Check if the xlate timer is set greater than or equal to what the conn timer, so as not to have connections waiting on xlates that no longer exist. To minimize the number of attempts, enable "service resetinbound" . The PIX will reset the connection and make it go away. Without service resetinbound, the PIX Firewall drops packets that are denied and generates a syslog message stating that the SYN was a denied connection.

Opening and closing Multiple TCP connections issues

Hi all I am having an issue with the TCP VI’s and wondering if anyone has experienced this issue.
My application is required to scan 50-100 IP addresses (statically assigned) and discover if an Ethernet device is connect at that IP address. Currently I am able to achieve this by opening a TCP connection and testing the error cluster to determine if a timeout has occurred (no timeout error means Ethernet device available at the IP address). I then ensure that the TCP connections are closed.
The issue I am have is that I require a 1 second delay between the TCP open and the TCP close which significantly slows down the process. Without the 1 second delay the vi successfully connects to the device once then fails to make any TCP connect regardless of the time delay until the PC is reset.
If anyone has any advice I would be very grateful
David Barr
P.S. I have attached a simplified section of code showing this issue
Attachments:
TCP Open close issue.vi ‏15 KB

smercurio_fc wrote:
If I understand you correctly you want the time delay to be 1 second if there's a successful connection....
While I don't have a specific answer for this problem. I want to clarify for him. I believe the issue is, what if all connections ARE there? That means you keep returning a wait of 1 second 50-100 times so It takes 50-100 seconds just to initialize. I think the user is looking for a way to check for valid connections, but do so in such a way that eliminates the need for a wait which is greatly slowing things down.
CLA, LabVIEW Versions 2010-2013

Anyone else having an issue with TCP connections using iCloud for Windows?

Hi,
Before I asked this question, I did wait to see if any related questions came up, but none did, so I submit it now.
On my admittedly older laptop running Windows 7 64b Home, I've run into difficulties with the iCloud for Windows app to the extent that I had to uninstall it.
It would that, as my laptop was running, in the background, iCloudServices.exe would endlessly iterate TCP connections, which, while not actively sending or receiving any data, after some hours would number over 100 instances, taking up resources, and grinding my laptop's WiFi connection to a grindingly slow pace. I ended up, within the app, turning off everything, iCloud Drive and Photos, (I never used bookmarks), but still this would continue to occur.
I contacted Apple Support, explaining what was going on, and they stated they only dealt with IOS and gave me a Microsoft Support number. When I called Microsoft support, I came more and more to the realization that the issue was specifically with the iCloud for Windows app, as that was the only software that was endlessly creating and not closing TCP connections as it was. How was Microsoft supposed to solve an issue with Apple code?
So I called Apple back, whereupon they insisted it was a Microsoft issue. I explained other cloud services installed on the same computer were not having the same issue, it was unique to ICloudServices.exe. They stated they only dealt with IOS. I stated I purchased an iPad Air less than 7 months ago, and was trying to run iCloud in support of that. They again stated they only dealt with IOS, and suggested I again try Microsoft. I asked them if it was reasonable to expect Microsoft to solve issues with Apple code? They said regardless, there was zero support offered for anything having to do with Windows, and all I could do was uninstall the app, which I did, though that did not feel very satisfactory to me. My thinking is, if Apple writes a Windows app in support of their hardware, they should offer support for it.
Anyway, I was just wondering, is this an issue unique to me? or have others experienced a similar issue? I found this issue by opening the Windows Resource Monitor, looking under the Networking tab, and scrolling through the TCP Connections section to find 100+ concurrent iCloudServices.exe instances listed, whereas even Chrome, with multiple tabs and extensions, topped out at around 20.
My one month old Desktop, DYI, sports a solid Asus 1150 MoBo, i7-4790k cpu, 16GB Ram, and an EVGA GTX 970 video card. I list some specs only to illustrate this computer has no hardware issues in comparison to my long in tooth laptop. On this desktop, running Win 8.1 Pro 64b, at least as many, identifiably Apple, background service TCP connections are created even compared to Chrome, regardless of many tabs being open, many extensions, and even some related apps. Adobe does not even come close, though I run the full CC subscription. On this new computer, running Windows 8.1 Pro 64b, there are currently over 50 TCP connections and loopbacks that do not identify themselves, with just a - for the Image, and PID. With the experience on my laptop, I wonder how many of these are generated by Apple software, if not specifically iCloud software?
The frustrating aspect of these connections is they seem in no way active, While the Chrome and Adobe connections can be seen to be transferring data, as long as I am not running iTunes, or so have my iPad actually plugged in, it seems 99% of the time these iCloudServices.exe connections are just taking up ports, neither sending nor receiving any data discernable to me under the Processes with Network Activity, or Network Activity lists, both displayed in the same window as the TCP Connections in the Windows Resource Monitor.
Though I am fairly ignorant as regards coding, it seems as if there is no call to close a connection, very specifically, iCloudServices.exe, when it is no longer needed, and the next time a connection is needed, a new one is opened, rather than accessing the one previously opened. The only other reason I could imagine this might be occurring is if my Norton Internet Security software might mask and/or block the port after a certain time of inactivity.
Anyone out there have any ideas or advice about this? Thanks in advance.

Thanks jared,
I'm still dealing with this issue through Apple. Some time after I posted this, I contacted Apple again. They did start a case up for me, as I was experiencing the same behavior on two different machines, with two different versions of Windows.
So far it remains unsolved. I've logged iClouds for Windows on my desktop, which is brand new, then logged for awhile after completely uninstalling Norton Security Suite, depending on the Microsoft security for some time, and finally logged after I uninstalled iCloud for Windows, restarted, installed a clean download, and connected using a completely different test account, which Apple set up for me. None of this made any difference. Looking at the logs, it seems every 10 minutes, iCloudServices.exe creates a new TCP connection to confirm I'm using less than 5GB on iCloud, (which I am by a good margin, using less than 2GB), it seems this connection is not closed, and when the next iteration rolls around 10 minutes later, a new TCP connection is created. I come very close to having 6 TCP connections created per hour, until I restart my computer. This works out to... 6 x 24 = 144/day.
Perhaps the article you posted will shed some further light on this. I'm thinking seeing the state of the connection through netstats, at the least, could help.
For the last week, I've been putting a hold on further logging, as Apple wants me to create a new user account on one of my computers, install iCloud for Windows there, and log it running in the other account. This however basically means I cannot use my computer for a fair number of hours, and I've been busy enough with work the past week that I haven't the time or energy to afford to set this up and run it. I've had need of my computers too much for the past week.

TCP connection error when sending MODBUS commands to WAGO 750-881 controller after 113655 bytes of data have been sent

Hi all,
I am new to the world of labview and am attempting to build a VI which sends commands to a 750-881 WAGO controller at periodic intervals of 10ms.
To set each of the DO's of the WAGO at once I therefore attempt to send the Modbus fc15 command every 10ms using the standard Labview TCP write module.
When I run the VI it works for about a minute before I recieve an Error 56 message telling me the TCP connection has timed out. Thinking this strange, I decided to record the number of bytes sent via the TCP connection whilst running the program. In doing so I noticed that the connection broke after exactly 113655 Bytes of data had been sent each time.
Thinking that I may have been sending too many messages I increased the While-loop delay from 10ms to 20, 100 and 200 ms but the error remained. I also tried playing with the TCP connection timeout and the TCP write timeout but neither of these had any effect on the problem.
I cannot see why this error is occuring, as the program works perfectly up untill the 113655 Bytes mark.
I have attached a screenshot of the basic VI (simply showing a MODBUS command being sent every second) and of a more advanced VI (where I am able to control each DO of the WAGO manually by setting a frequency at which the DO should switch between ON and OFF).
If anybody has any ideas on where the problems lie, or what I could do to further debug the program this would be greatly appreciated.
Solved!
Go to Solution.
Attachments:
Basic_VI.png ‏84 KB
Expanded_VI.png ‏89 KB

AvdLinden wrote:
Hi ThiCop,
Yes the error occurs after exactly 113655 bytes every time. The timeout control I would like to use is 10ms, however even increasing this to 1s or 10s does not remove the error, which leads me to believe that this is not the issue (furthermore, not adding any delay to the while loop, thus letting it run at maximum speed, has shown that the TCP connection is able to send all 113655 bytes in under 3 seconds again pointing towards the timeout control not being the issue here).
I attempted Marco's suggestion but an having difficulty translating the string returned into a readable string, (rightnow the response given is " -# + ").
As to your second suggestion, I implemented something similar where I created a sub VI to build a TCP connection, send a message and then close the connection. I now build each message and then send the string to this subVI which successfully sends the command to my application. Whilst not being the most elegant method of solving the issue, it has resolved the timeout problem meaning I am able to send as many commands as I want. So in that sense the problem has been solved.
If you still have tips on how to correctly read the TCP read output, I would however like to see if I could not get my first program to work as it is slightly more robust in terms of timing.
Modbus TCP RTU is a binary protocol, as you show in your Basic VI, where you format the data stream using byte values. So you have to interprete the returned answer accordingly with the Modbus RTU spec in hand. Now what is most likely happening is that the connection gets hung after a while since you do NOT read the data the device sends as response to your commands. The TCP/IP stack buffers those bytes and at some point the internal buffers overflow and the connection is blocked by the stack. So adding the TCP Read at strategic places (usually after each write) is the proper solution for this. Is there any reason that you didn't use the NI provided Modbus TCP library?
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

How to send joystick data over TCP connection

Hi all,
I am a long time Labview discussion forum user for learning, but this is my first time posting a question, I hope somebody can help me!
In the attached VI I am trying to send data from a joystick over a TCP connection. I can send data fine using the TCP examples (in fact the majority of my VI is just a copy of the example). However I am to the point where I do not know how to send all the data necessary (3 axis data, 12 buttons, and the POV data) over TCP. Strings, clusters, and arrays were never my strong suite and converting between them is a nightmare for me.
Basically I am trying to send each axis data (X,Y, and Z), button data (12 buttons), and POV data (the POV data will be calculated to adjust the position of a camera, so the immediate data is not important, I will add functions to add the change in the button movements to write a standing position for two servos [pan and tilt], for which that I will need to send over the TCP connection) over the TCP connection to control various cameras and motors. I don't know if it is posible to send that much data over a TCP connection in one write VI through a string, and also how to separate the string on the other side in order to control the client VI.
Again, the actual TCP communication I get, and can operate fine, just formatting all the data into a string (or whatever is required) so that I can unpack on the other side is the issue here.
Another question I have (not impotant to get the program running just might make it easier on me) is can a TCP server (which sends the data to the client) also recieve data back from the client on the same port ( for example sensor data and digital positions [on,off])? Or do I need to set up two TCP communication loops with the first client acting as the server on a different port than the first, which then sends the data to the original server, which also has a client TCP configuration in another loop? I hope this makes sense...
One final question.....I already have a solution to this but using labview for the entirety of this project would be nice. I use skype to stream 1080p video from a webcam to my computer so I can view live feed. Can labview do this? This would be awesome if so, I am just not sure if the communication protocols in use could support real time (or as close as possible to streaming) for 1080p video.
Thanks all in advance for your help,
Physicsnole
Attachments:
cameraserver.vi ‏24 KB
cameraclient.vi ‏18 KB

Physicsnole wrote:
In the attached VI I am trying to send data from a joystick over a TCP connection. I can send data fine using the TCP examples (in fact the majority of my VI is just a copy of the example). However I am to the point where I do not know how to send all the data necessary (3 axis data, 12 buttons, and the POV data) over TCP. Strings, clusters, and arrays were never my strong suite and converting between them is a nightmare for me.
Well, you cast the axis info cluster to a string, but then you cast it back to an array of DBL. Thatr's not compatible. You should probably cast it back to an "axis info" cluster of exactly the same type. Go the the other VI and right-click the cluster wire to create a constant. Now move that diagram cluster constant to the other VI and use it as type.
Your default ports don't seem to match. You seem to have client and server roles confused. In the sever you create a listener, but then you start sending packets, even though no connection is established. The connection needs to be initiated by the client.
Your client stops the loop the first time a timeout is encountered. Shouldn't that be more permanent? Also, please retain code clarity and avoid unecessary complexities. For example, replace the "not or" with a plain "or" and change the loop to "stop if true"
Physicsnole wrote:
Basically I am trying to send each axis data (X,Y, and Z), button data (12 buttons), and POV data (the POV data will be calculated to adjust the position of a camera, so the immediate data is not important, I will add functions to add the change in the button movements to write a standing position for two servos [pan and tilt], for which that I will need to send over the TCP connection) over the TCP connection to control various cameras and motors. I don't know if it is posible to send that much data over a TCP connection in one write VI through a string, and also how to separate the string on the other side in order to control the client VI.
You can send as much as you want. The casting to/from string is the same as described above.
Physicsnole wrote:
Another question I have (not impotant to get the program running just might make it easier on me) is can a TCP server (which sends the data to the client) also recieve data back from the client on the same port ( for example sensor data and digital positions [on,off])? Or do I need to set up two TCP communication loops with the first client acting as the server on a different port than the first, which then sends the data to the original server, which also has a client TCP configuration in another loop? I hope this makes sense..
The primary function of a "server" is to wait for a connection and then communicate with the client once a conenction is established. An established TCP/IP connection is fully two-way and both sides can send and receive.
LabVIEW Champion . Do more with less code and in less time .

Connect to a printer via TCP connection with wifi

Hi,
what i would like to do, is to connect a printer to the iPhone via wireless.
The printer is in the same wifi as the iPhone and the ip adress is known.
So what i started to to is, to create a SocketConnection with CFStreamCreatePairWithSocketToHost(...). But if i switch of the printer, the inputstream is created too, and is not NULL as expected.
Is this the right approach im using or is there a better possibilty to send strings to my printer using a tcp connection over wifi?
Regards,
Grinarn

Welcome to Apple Discussions!
In the Help menu of the Finder is a little app called Mac Help. Most Apple apps and many 3rd party apps also use Mac Help. In Mac Help is an article called *Adding a printer shared by a Windows computer via SMB/CIFS*. This article is regarding sharing a printer that is connected to a PC over a network however, and not to a router, but may have info useful to troubleshooting. You might also check with your Linksys user guide for info on sharing this printer with a Mac over the network.

How to prevent a TCP connection being closed when the VI that opened it finishes.

Hello everyone.
I am developing an application based around servers and clients communicating over TCP in LabVIEW 2012.
When the server/client opens a TCP connection ,it launches an asynchronosly running "connection handler", to which it passes the connection reference which then takes over all the communcation. This all works fine.
However - I have a situation where a client's connection handler can be informed of another "new" server. I would like it to open the connection (to see if it is still valid) and then pass this connection reference back to the client's main code to spawn a new connection handler. This prevents me locking up the Client's main code with a long-ish timeout if the "new" server is not actually accepting connections.
The issue is that if the connection handler that opened up the connection to the "new" server is stopped, then it appears to destroy the reference that it opened. This means that the other connection handler that was merrily communcating with the "new" server has its TCP communciations closed (I get an Error code 1 on a write).
I have created an example to demonstrate the issue which should be used as follows:
1. Run server.vi - it will listen for a connection on the port specifed on its BD.
2. Run CH Launcher.vi - it will open a connection to the server and pass the TCP reference to an instance of Connection Handler.vi which it launches.
3. The Connection Handler should send data to the Server
4. Stop the CH Launcher.vi
5. The Connection Handler.vi will error.
Any suggestions would be much appreciated.
Cheers
John
Solved!
Go to Solution.
Attachments:
TCP Test.zip ‏35 KB

John_Neutron escreveu:
In my case I have changes the part of the code that opens the TCP connection to a VI that has the same lifetime as the main VI so that any connections that have been opened will only be closed automatically when the main VI stops.
And what are the effects? You are still facing the same problem or closing the connection only when the whole applicaton stops solved your problem?
Regards
Mondoni

TCP connection in labview and C program

Hi there,
I have a server program written in C and running under linux, it
accept connection from client and send series of data to client
through TCP socket. I was using the "simple data client.vi" as the
client.
I tried to send integer number 1, 2,3.. , but the client failed to
correctly decode the data since it read everything as string. I was
wondering if there is a solution to read binary data in labview TCP
connection? I really don't want to encode the double into string and
send it to client through TCP socket in my server program, since it's
not efficient.
thanks !

> I have a server program written in C and running under linux, it
> accept connection from client and send series of data to client
> through TCP socket. I was using the "simple data client.vi" as the
> client.
> I tried to send integer number 1, 2,3.. , but the client failed to
> correctly decode the data since it read everything as string. I was
> wondering if there is a solution to read binary data in labview TCP
> connection? I really don't want to encode the double into string and
> send it to client through TCP socket in my server program, since it's
> not efficient.
> thanks !
>
The string is often used in LV as a general buffer. Type Cast the
string as the appropriate integer and it should be fine. If the integer
has been transmitted in litt
le endian byte order, you will need to use
the Advanced byte and word swapping functions in LV in order to reorder
the integer contents -- LV always assumes big-endian binary format.
Greg McKaskle

Forefront TMG disconnected a non-TCP connection

Hi,
I am getting the following error alerts in TMG
Forefront TMG disconnected a non-TCP connection from 192.168.0.1 because the connection limit for this IP address was exceeded. Larger custom connection limits should be configured for the IP addresses of chained proxy servers and back-to-back Forefront
TMG computers with a NAT relationship.
This error show two msgs for my both dns servers.
My DNS servers Ip addresses
192.168.0.1
192.168.0.2
Please help me out
Thanks

Hi,
How about editing the Maximum non TCP sessions per second per rule setting?
For more information:
http://technet.microsoft.com/en-us/library/dd441028.aspx
Best Regards,
Joyce
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