stars_n_moons22

Hi Graeme, Just to update you, I had a closer look at my code and I was already closing the connection IDs as well as the listener IDs but I don't think my program was being left long enough before trying to reestablish the port connection as you mentioned in your post. As for the white functions, I tend to think of them as helping hands to get me going on something new. In some instances I find that they can get you up and running by getting most of what you want done without having to dive straight for the advanced functions. But also, if I get stuck on something a bit more advanced I can delve into these for some hints and tips on what I might be missing from my own code. Just my opinion tho! Sam

Hi Graeme, I'm having some similar problems with TCP connections. (Unfortunately, it's code I've inherited from someone else and let's just say it's not as optimised as it could be...!) I've encountered a situation exactly as described in the NI page that you talked about. We create a listener and then do a wait on listener. On closing the connection we only close the Listener ID and not both the Listener ID and Connection ID and we've been wondering why we then have to shutdown LV completely before we can establish a new connection to that port! I'm going to be trying this fix in my code and then doing some tests to make sure it works so I'll keep you posted on the outcome. Sorry I can't offer any more help than that at the moment, but Good Luck in sorting your problem! Sam

Thanks for the input Tom and Louis. To answer your questions Tom, I am opening and closing the TCP connections each time I send something to the printer. Also, there aren't more printjobs but there seems to be alot more network traffic than previously and I haven't tried to monitor the number of socket connections using netstat only the number of socket connections on my MySQL database. - BUT I will definately be monitoring them now! From what you have both said i think one of two things might be happening. 1. As I open a seperate TCP connection and port each time I connect to my printer, I end up using too many ports and no more ports can be allocated so I can't communicate to the printers anymore until I clear out all the unused ports by restarting my apps. OR 2. On one call to the printer, I fail to close the TCP Connection succesfully to the printer so the next time I try to connect to the printer, it throws me out as it thinks it already has a connection established waiting to be used. I think that this might be more likely as there has been a rewiring of the network recently and from other projects in the same area, it looks like one side of the network (including where my printers are) is getting completely overloaded at certain points of the day. I think that when one of these overloads happens, it interferes with closing the TCP Connection to the printers and stops me from establishing any new connections. I think my next stop will be to monitor all the socket connections using netstat and also to try to check out all the network traffic with packetyzer and try and see what exactly is happening with the TCP connections when this happens again. Then I will probably think about how I could manage keeping the TCP connection to the printers open all the time rather than opening and closing each time. Thanks to both of you for all your help and relating your similar experiences - it's been invaluable in getting my little grey cells working in the right direction! (And has saved me from another day of and :headbang: !) Cheers! Sam

Hi Louis, Thanks for the welcome note, I've been a lurker for a while but not posted before. Thanks for the lead on the Printer flash firmware, I'll look into that. I don't think they update themselves but since I don't control them I'm not sure how they do it so it's good to be a bit paranoid under the circumstances! As for the TCP connections build up, each time I connect to one of the printers, I open the TCP Connection, squirt the data down the line and then use the TCP Close connection. I guess that the printer might not have closed it's connection properly but then the next time I tried to connect to it wouldn't I have got an Error 66 - The network connection closed by the peer? Also why would the refusal of a connection by 1 printer cascade down to all my other printers? Could this have been caused by some kind of distruption on the network which would mean that the printers never saw me close the TCP Connections and so would not allow me to connect again (Assuming that they only allow 1 TCP Connection at a time)? Thanks very much for your kind help - it's been very useful Sam

Hi Everyone! I am running two Labview exes on a server PC. These two exes are communicating with different bits of hardware over TCP Connections. I am having problems with one of the executables TCP Connection to a printer. I will be able to send commands from the exe to the printer to print labels for hours on end and then suddenly I get an error saying that the label failed to print. (I don't log that specific TCP error at the moment.) At this point usually, several other printers running from this exe will all experience the same problem and stop printing. If I close down and then restart the exe that deals with those printers, I get a TCP Error 61 when I do an initial startup connection to a MySQL Database that I am using. The error is described as Serial port parity error or The System could not allocate the necessary memory. I'm not sure whether to believe this error or not since the PC has plenty enough memory. But this means that my exe will not even startup. If I close both the exes that are communicating over TCP and restart them, I get no errors and my printers start printing labels again. After this had happened a couple of times, several hours apart, I was a bit flummoxed as to the root of the problem. So, Great Labview Gurus, do you think that this problem is: 1. more likely to be caused by something happening in the program (BTW The printing code has been used for over a year with no changes and this is the first time I've seen this problem) or 2. a strange memory error on the PC or 3. some other funny thing happening on the network when my printer first reports an error or 4. Something completely different Many thanks in advance for any help or advice! Sam Labview 7.1.1 MySQL DB 4.1.16 Windows Server 2003