Switch corrupting my data??

[stu22]

Hi, testing my connections to my remote OPC server. It passes data through a manageable switch, which is connected to the main network. I disconnected the main network connection from the switch, while my labview program was running. It uses a datasocket in the program to read data from a Remote OPC server. So it should now pass data purely through the Switch. Which it does intially, but then after a while the data gets corrupted or lost and i start to get no results. Anyone know what could be happening??

[Owen.S]

Hi Stu22,

Does the corruption only happen after you disconnect the switch from the network?

Where abouts is your remote OPC server?

How long does it take for the data to become corrupted?

Kind regards,

[stu22]

Hi Owen S, yes corruption only happens when disconnected from the network. The Remote OPC server is on a PC conected to the switch and my 2 OPC Clients on separate PC's. It may take an hour or can happen immediately for data to be corrupted.

Stu 🙂

[Owen.S]

Hi Stu,

Do you have another switch you could try? Or perhaps try some of the other ports on the switch?

Is there a reason why you have to disconnect from the network?

Kind regards,

[stu22]

H Owen S, the switch has 24 ports and im using them all, eek!! The reason why we disconnect from the main network, is that it can be unreliable and drop connection. So i would lose my instruments. The switch is there so that doesnt happen. As these PC's with instruments are in our lab, are connected to the main network. Could the security settings or group policy be affecting it??

[Owen.S]

Hi Stu22,

Is there any way you could remove all switch connections apart from the ones for your OPC server and client computer?

I'm not sure that security settings would corrupt data.

Kind regards,

[Mark_Yedinak]

Have you tried using an network sniffer like Wireshark to capture the traffic? Barring a network analyzer would you be able to run NI Spy to capture the data? Are you sure that the data corruption is occuring at the network level and not in your application itself? What type of switch are you using (brand and model)? Do you know how it is configured? Can you query the switch for any logs or events? What are the addresses of your devices? Are you confident that you don't have any duplicate addresses in your network? Are your applications trying to communicate with something outside these devices such as a DNS or DHCP server? This could be why it only occurs when you disconnect from the main network.

Dropped connections can be an application issue if the applications specifically close connections after some specified time of inactivity. There could also be bandwidth limits defined which may drop connections after a specified threshold.It would be very rare for a switch to corrupt data unless it is specifically configured for some type of thresholds or filtering or if it is configured incorrectly. This type of issue is generally caused by a bug in the application or problem in the network infrastructure.

Based on your description of what is happening I would look at the network configuration to see if something is misconfigured.

Message Edited by Mark Yedinak on 06-11-2010 10:27 AM

[stu22]

Hi, will try that one. But did a test today, with labview datasocket as the client and a client supplied with OPC server. And disconnected the network, what happen is that, one by one the clients started to recieve no data. Even the client that was supplied with opc server stopped recieving data. the only client that worked was the local one. i did a check with an example supplied by labview examples. the example creates opc addresses, it came with an error "could not enumrate??" i think it means it can not see the items on the opc server after +-10 minutes. But yet it can detect its ip address. If it could not, normally it would freeze labview and crash the opc server supplied client.

[stu22]

Hi, as in my reply to the other post i suspect its to do with network. it may also not be corrupting the data. the datasocket gives an error of number 42, datasocket read error. I presume thats because it isnt able to see the items on the OPC server.

Stu

[stu22]

Hi, it seems that when the network is disconnected. The ip's for the opc are lost, but not for the fieldpoint connection. Presumably its because fieldpoint uses a different address structure and just requires ip's not to look for. As opc requires to look at the DNS for ip's. How can we stopped this??