Fabios Posted March 1, 2014 Report Share Posted March 1, 2014 In your example (V120_GPRS_sony_ericsson_wavecom.vlp) you write: "However, in all GPRS applications, the PLC must initiate the GPRS data link by calling the PC." Why this? There is the FB "Listen to Remote Device". If i understand well, with this FB PLC wait that someone call it. So there are 2 possibility: 1) PC call PLC (PLC in Listen mode) 2) PLC call PC (PC in listen mode) Do I missed some concept? BR Fabio Quote Link to comment Share on other sites More sharing options...
Fabios Posted March 1, 2014 Author Report Share Posted March 1, 2014 My be i understand! May be you mean that with plc in listen mode it is no sure system! Everybody can connect to plc! Can you confirm this? BR Fabio Quote Link to comment Share on other sites More sharing options...
MVP 2014 Simon Posted March 2, 2014 MVP 2014 Report Share Posted March 2, 2014 The main issue is not anything inside the PLC or Visilogic - it is with the way telco providers handle IP addresses with GPRS connections. With GPRS (and other types of cellular broadband) the remote device can call out to you, but you can't easily call into it. So the PLC can call back to your PC easily. But if you put the PLC into listen mode and try to call it from your PC, the PLC will never receive the call. This is because the GPRS connection does not allow you to call the remote device. The IP address that the modem is given on the GPRS connection is usually a firewalled, private IP address, on its own subnet. Exceptions are: * public IP address on SIM card and use dynamic DNS * fixed, public IP address on SIM card * use a VPN If you don't have any of these exceptions available to you , then your only option is to have the PLC initiate the call and have your PC in "listen" mode. Quote Link to comment Share on other sites More sharing options...
Fabios Posted March 7, 2014 Author Report Share Posted March 7, 2014 >The IP address that the modem is given on the GPRS connection is usually a firewalled, private IP address, on its own subnet. Is it possible to ping these IP address? Quote Link to comment Share on other sites More sharing options...
MVP 2014 Simon Posted March 9, 2014 MVP 2014 Report Share Posted March 9, 2014 If the IP address is a firewalled, private IP address, you will not be able to ping the modem directly. When the modem is connected in GPRS mode the Unitronics examples normally display the IP address, or you can view it in hyperterminal. If you can ping this IP address, then it would appear you have a public IP address on the SIM card. Assuming this is the case, if you change the example to set up the GPRS in listen mode, you should then be able to connect from Visilogic using the Ethernet call method. However I would also try the recommended method first, that is getting the PLC to initiate the call to a PC in Listen mode. This is simpler and helps confirm that all the basic steps are correct. Without trying to be unduly negative, this process works well when it works, but is not "plug and play". It usually takes some testing and debugging. Quote Link to comment Share on other sites More sharing options...
Fabios Posted March 11, 2014 Author Report Share Posted March 11, 2014 Simon, with Visilogic in Listen mode all work perfectly. My dubt was born when you say: >The IP address that the modem is given on the GPRS connection is usually a firewalled, private IP address, on its own subnet. In this case I wouldn't able to ping modem IP. Instead I'm able! Quote Link to comment Share on other sites More sharing options...
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