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MAS 21: Errors in GPRS communication

Created by: Beep-A at: 2/26/2008 4:12 PM (22 Replies)

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2/26/2008 4:12 PM	Rate (0)
Beep-A Posts: 90 Rating: (1)	Hello to all... We are running the WinCC V6.2 Runtime on a PC with the standard Ethernet card. On the same PC is running the MicroSC OPC server for GPRS communication with 5 S7-200 PLCs with MD720-3 GPRS modems (one of the stations is now out of service, so we have a communication with 4 stations). The system worked fine for 3 months (reading and sending the data from/to PLC), but for the past two months something strange is happening. All OPC connections, from the modems, are connecting and disconnecting from the MicroSC OPC server every 2-5 minutes. The first thing that I suspected was the DynDNS service, but for one day, I've entered directly the IP address of the PC and the stations behaved the same way. In the attached file you can see the log file from MicroSC OPC server. From the logfile you can see that there is some problem with reading on socket, but unfortunately we don't have documentation of the CTSCPClient function. The PLC status monitor is: Status monitoring by value updates – for every 30 minutes. Does anybody have similar experience? What could be the reason for such errors and what can be done to resolve these problems? Thanks in advance for your answers. Beep Attachment m2mopc_log.zip (536 Downloads)
Beep-A Posts: 90 Rating: (1)	Last edited by: O_Moderator at: 4/15/2010 8:14 AM subject edited
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2/27/2008 8:37 AM	Rate (0)
Lifrasil Bronze Member Joined: 9/29/2005 Last visit: 11/15/2024 Posts: 313 Rating: (24)	Hi Beep, always when i see such a failure description in the m2mlog i am very afraid . Those f***** "Read on socket failed" can be caused by everything. From the Remote Station to the IT-infrastructure of your company. General it means, that anywhere a TCP/IP packets timeout was exceeded. So the Server thinks the Remote Station is offline. Some more question: + What goes offline? Modem or PLC or both? + After going offline: Is the Station online again in a few minutes? + Do you have the possibility to upload the Logfile from the Modem? (Please make a firmwareupdate before. the V1.7.7 show the system messages in clear words. When you download the Logfile with a FW Version before V1.7.7 you have to send it to the customer support. Because with those cryptical entries there i can´t unterstand anything) + Please explain your local IT infrastructure from the DSL connection to the SINAUT Micro SC Server regards Lif

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2/27/2008 2:59 PM	Rate (0)
Beep-A Posts: 90 Rating: (1)	Thank you Lifrasil for your answer... Here are some answers to your questions: Looking from MicroSC OPC server it seems that both the modem and PLC go offline; The parameter MSC:[station_name]PLCConnected is false; But on the PLC side everything is working normally (the PLC is in Run Mode without errors) Yes, after that the station goes offline, it reconnects after few minutes (can be seen from the log_file) The modems have firmware version 1.7.4. At the moment I can't update the firmware. We'll be on the site next week, so then I can try with the new firmware. The PC is located in the office and is on LAN with other PCs. The LAN is connected to the router. On the router is configured the virtual server that has port forwarding to the IP of the SCADA router with port 26862. The router is working and has no restriction. First, I suspected that the malfunction is created by intense internet traffic from other PCs, but the same thing is happening through the night when there are no employees. I checked the proprieties of the network card and disabled the standby functions but the problem remains... The strangest thing is that a few months ago everything worked fine... Do you have some other idea, what to try next? Thanks in advance Kind regards Beep
Beep-A Posts: 90 Rating: (1)	Last edited by: Beep-A at: 27.02.2008 15:00
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2/28/2008 8:54 AM	Rate (0)
Lifrasil Bronze Member Joined: 9/29/2005 Last visit: 11/15/2024 Posts: 313 Rating: (24)	Hi, ok, lets hunt the needle in a bundle of hay. (Is this also a english idiom? ) General: The communication between S7-200 and MD720-3 is unidirectional with the higher priority on receiving (from the S7-200 view). This means its nothing abnormal when there is a crash because of e.g. Sending from S7-200 to Server crashes with Status monitoring of Server to s7-200. This appears frequently with the combination of a short monitoring cycle on SINAUT Micro SC´s side. But you told me you have a monitoring cycle of 30 Minutes. So this event should occur very rarely. Looking to the logfile show me that its quiet frequently. To your system: 1 Do you have the possibilty to install a port analyzer like "commView" Download Would be nice to see the relation between " 26.02.2008 13:12:19.637 ERROR: CTSCPClient::Read(): ("modem2") Reading on socket failed! Closing session. WSAECONNRESET " and some lost TCP/IP Pakets or to long Response times. 2 Can you be sure that on the remote station side no power failure causes this problem 3 Whats the signal strength and the signal quality (any motors, cable for electricity nearby of the MD720-3) 4 Could you please contact the provider for any eventual provider problems 5 Where do you live? Actual in Austria and Argentinia there are known provider problems. regards Lif

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2/28/2008 11:25 AM	Rate (0)
Beep-A Posts: 90 Rating: (1)	Hi Lifrasil Thank you for searching the needle with me.Here are some answers to your questions: I'll contact the client and manage to install the network analyzer like commView as you suggested. I'll try to track the packet regarding ERROR: CTSCPClient::Read(): and hope to find the relation and the cause of the error. I've double-checked that there are no power-failure on the stations The signal strength is excellent or very good (the "Q" LED is permanently on or is blinking 3 times in a raw). The modems and PLCs are installed in typical enclosures for pump stations. The power of the pumps is around 4kW and there are no frequency converters or soft-starters. The location of the modem is away from any switched power supply. I've contacted the provider and the technical support told me that there are no change/problems in their configurations data and that no one reported similar problems. In the next week I'll try one station with another GSM provider to exclude this possibility The site is in Croatia and the provider is T-COM. Like I said, thanks for the help. I hope that this needle will arise from somewhere Kind regards Beep
Beep-A Posts: 90 Rating: (1)
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2/28/2008 3:28 PM	Rate (0)
Lifrasil Bronze Member Joined: 9/29/2005 Last visit: 11/15/2024 Posts: 313 Rating: (24)	Hi, no problem! 1. Ok simple advise him to check for incoming and outgoing traffic on port 26862. He should check the time of "...socket failed..." in the logfile and compare it with the time of the incoming and outgoing traffic on this specified port. 2. Damn, this would be so easy for me 4. Ok thats what they always say but up to now let´s trust them How often do you send from Remote Station to Central Station? Or is the 30Minutes polling cycle of your central station the only data amount? Do you use SMS/Teleservice? regards Lif

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2/28/2008 6:02 PM	Rate (0)
Beep-A Posts: 90 Rating: (1)	Hi, again, Lifrasil I've installed the commView software on the SCADA-PC and monitored the port 26862 for traffic with one station. The log file of the m2m_opc and the excel file of the commView log are in the attachment. Probably the clocks in these two files are not synchronized, but I've noticed one thing. When I have "read socket failure" the port of the GPRS station has changed! You can check it in the log files. Could this be the cause of these reading failures and constant connecting/disconnecting of the stations? Is this a meter of the provider, or can be controlled by the user?The sending from the Remote station is event driven. For example when the pump is ON or when the max level of the tank has been reached. Let's say that the stations are sending data every 15-20 min. We use SMS service if there no one acknowledges the alarm on the SCADA-PC for 10 minutes. When this kind of read socket error happens, the remote station in not in the SMS mode of operation – this has been checked. Kind regards Beep Attachment log.zip (467 Downloads)
Beep-A Posts: 90 Rating: (1)
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2/29/2008 8:35 AM	Rate (0)
Lifrasil Bronze Member Joined: 9/29/2005 Last visit: 11/15/2024 Posts: 313 Rating: (24)	Hi you! ok i can´t see anything in this logfile because without a correct relation regarding the timestamp i am not able to figure out there anything. But regarding to your comment: The MD720-3 arrange a port from 1024 to 65xxx with the providers Router/Server. This port will be only open for a while to ensure that there are always enough ports open for any request. Such a port will be only closed when there is a timeout regarding any TCP/IP paket. To answer your question: No, from this point of view we can´t do anything. But fixing the reason for the timeouts will also ensure that the same port is used for a long duration. So from this point of view we don´t know if the timeout is caused by the Modem (i don´t think so), by the mobilephone provider, by the dsl provider or by your local infrastructure. But look at following thing: Your remote station keep always the Ip-Address. So i don´t think that its disconnected because then (ok not always but sometimes) would get a new ip address. This is what you can ask your provider once again. "Will my machine get a new ip-address after GPRS connection got lost?" Because with this behavior each provider deals in an other way. ok, and please use once again the commview analyzer with the correct timesettings. and also please ensure that you will use the option "File/Save Packet Log as" and use the *.ncf format. Because then i can open it with my com view here. regards Lif

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2/29/2008 5:16 PM	Rate (0)
Beep-A Posts: 90 Rating: (1)	Hi Lifrasil Here are the log file of commView saved as NAI Sniffer for Win and the appropriate m2m_opc log file. So, you can check the packets. In the next week I'll check with the provider what you suggested and also change one station to another provider to eliminate this option. Thank you for your answers and suggestions. Kind regards Beep Attachment LOG.zip (439 Downloads)
Beep-A Posts: 90 Rating: (1)
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3/1/2008 1:31 PM	Rate (0)
uel123 Gold Member Joined: 1/29/2006 Last visit: 11/12/2024 Posts: 447 Rating: (64)	Hi ALL! I have nearly the same configuration (4 S7200 stations with GPRS Modems, Sinaut Micro OPC server, WinccFlex SCADA,......)in one application and also the same problem! *It is very interesting,that traffic goes OK during the night and during weekends!!!* Ialso tried to analyze my problem, with use of m2m log file and Ethernet traffic control program (some freeware, from internet,...). I have managed to mergelogs from both programs in one, which is attached. I have allready posted a question on Siemens support, and I have received a following answer: I quote: The meaning of message "ERROR: CTSCPClient::Read(); ("modem1") Reading on socket failed is that the provider cannot handle the huge traffic. It is rush hour at the net. If you have further questions don't hesitate to contact me again.Best regardsYour Technical Support for Automation & Drives End of quote. Now, I dont know, what to do. In my application, stations allways return back after some time (after 5 seconds (!), after few minutes, the longest time is about 12 minutes). I wouldalso be very happy, if anybody could give us a hint, what to do. Attachment SINAUT LOG AND ETH LOG MERGED.zip (452 Downloads)

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