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 Post subject: "No connection" message
PostPosted: Thu Feb 07, 2013 9:08 am 

Joined: Fri Jan 27, 2012 4:20 am
Posts: 166

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In my project there are 3 controllers:
1. FX3U_serial (COM4)
2. NMEA_0183 (COM2)
3. Modbus (Ethernet) for remote monitoring
When everything OK, no error messages. If a controller is disconnected, an error message appears on the screen. When after short time, the connection restored, the error message disappeares. But, when the Modbus controller disconnected for long time, for example, disconnected at 5 p.m. and tne next morning 8 a.m. connected again (PLC and HMI run all night), the error message does not disappear. The Modbus controller itself works OK.
The only way to get rid of the message, is to power down and up the HMI.
We use T7A panel. Why does it happen?
regards, Waldemar


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 Post subject: Re: "No connection" message
PostPosted: Thu Feb 07, 2013 1:05 pm 

Joined: Tue Mar 13, 2012 9:53 am
Posts: 824

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How do you know that the Modbus connection has been restored? The modbus Master controller should continuously try and reconnect to the Modbus slave. Maybe the slave is not responding to the Modbus master requests. Have you tried restarting the Slave rather than the HMI after they have been disconnected for so long?

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Mark Monroe

Beijer Electronics, Inc. | Applications Engineer


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 Post subject: Re: "No connection" message
PostPosted: Fri Feb 08, 2013 2:59 am 

Joined: Fri Jan 27, 2012 4:20 am
Posts: 166

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The task was remote monitoring through ethernet. I found an old VB6 Modbus program, which was used for monitoring a Scheider PLC on a Windows 2K PC, modified it and tried with T7A. As controller settings in iX Developer: Modicon> Modbus Slave RTU/TCP , were chosen. Another option (Modicon>Modbus Master) did not work. It works OK, shows values of tags and allows to set tag's values. What is confusing, I don't know where is actually Master and where Slave. I guess, the VB6 program must be Master, to be able to tell the HMI what to do?!
When after later restore, with an error message on the screen, the program shows correct tag's values and allows to set tag's values in PLC.
This morning I found the same problem with another controller: NMEA 0183. On the same PC (Windows XP) a GPS imitating program was running. On the HMI screen was correct GPS data and a message: no connection to NMEA 0183.
Next week I want to try laptop with Windows 7 to run these 2 programs.

regards, Waldemar


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 Post subject: Re: "No connection" message
PostPosted: Mon Apr 29, 2013 5:42 am 

Joined: Mon Sep 24, 2012 9:08 am
Posts: 11

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Hello,

I have the same problem in the T7A with Modbus communication than the user wlederer

If the server (it is a delphi program) closes communication with the HMI for a short while the message appears. When the communication program retrieves the message disappears without problem. But if the server closes the communication for a long time (hours), when the recovery, the message remains ... although Modbus communication works perfectly.

T7A I have to reboot to clear the message. In my case there is a serious problem because it is unusual, but it is annoying.

thanks!!

best regards,


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 Post subject: Re: "No connection" message
PostPosted: Mon Apr 29, 2013 8:32 am 

Joined: Tue Mar 13, 2012 9:53 am
Posts: 824

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Which iX Version are you using? What is the Modbus driver's version? What is the wording of the comm error?

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Best Regards,
Mark Monroe

Beijer Electronics, Inc. | Applications Engineer


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