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rajsiyer

SMS...ing using Twido & generic GSM modem

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Hi guys; I've been struggling for a week or so, with no success whatever to accomplish the following... A small twido PLC (CAE40DRF) must send an sms over the GSM network whenever an alarm condition occurs, with a suitable message. Other than that EXCH function which sends a modbus query to port; I'm not aware of any other comms functions in Twidosoft/Suite. Again, since the serial port on the CAE40DRf is MODBUS, I think one needs to obtain a 2nd RS-232 port for the SMS link. Is this right?? I'll genuinely appreciate advise and guidance for any help that you guys can come up with. Thanks a million, for looking in. Regards, bestt wishes raj s. iyer

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no raj you're not right! EXCH function is not modbus (not only) it depends on the configuration of the port. In effect you need to configure the port in charcter mode. After that you need a converter to change the elctrical support from RS485 to RS232: it means a cable converter TSXPCX1130 if you want to stay in the Schneider house or any 485/232 converter in the market. Each modem could have different type of connection so check the characteristic of your modem connection and buy or make your own cable. In the program software you have to use EXCH function (normally send and listen mode). Study well all AT commands for your modem in order to configure and use it as it was your cell. Good job

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Thanks Italiano; One thing, I failed to inform you,,, that old Advantys STB problem... if you remember?? I went back to site and replaced the Optical fibre/Ethernet convertor. This was what was causing the problem. Things are working fine now. The redundancy now is done without a ring topology. All switches are chained without forming a ring. Works well now. Coming back to the present problem of sending SMS.... I've made some progress today. It has not worked so far. First of all, I've installed the 2nd port as twd**232 so that theres's no converter issue. It has been connected by means of a straight serial cable (pins 2,3,5 only, no flow control) GSM modem. For linking the PLC's 232 port for debug on Hyperterminal, we've used a 2nd cable with RX & TX crossing. Both cables work. Using Hyperterminal(& straight cable) we're able to send a SMS from the modem, using the syntax AT+CMGS =<"mobile_number"><CR><message_body><Ctrl+Z>. This much is successful. Next, In the exchange function, we have sent a series of words to port (eg. 2) like EXCH2 %MW0:14. The contents of the words o-7 are initialised to read as AT+CMSG = "+919869438718"<CR>, wait 3 secs then again move EXCh2 %mw100:20. % mw119 contains <space><Ctrl+ z> ie %mw119:=16#201A. %mw100...118 is the body of the message. This did not work!!!! I am trying again tomorrow. I'm new to AT commands. To see what is coming out of the PLC's port we connected it to Hyperterminal. The first command is correctly displayed as AT+CGMS="+919869438718" then after a 3 seconds delay, we see Message_body -> AT+CGMS = "+919869438718" on the hyperterminal screen. However I get no SMS . Nobody in our team has a clue why Will tell you more tomorrow. Grazie a lot my friend. Plan to come to India anytime?? Raj S. Iyer

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Raj what happened. Did you succeed as I am working exactly on a similar project.

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