Hi
I'd like to share some of our experiences implementing a SMTP-Application using a serial modem.
Please see my other Threads in
We startet with the Telit Modem PCS-Version. After some time we had major problems with the internal timing in the modem. Some at-Commands must be handled very carefully not to make the Telit modem hang. for example: you ask the modem if it is connected to the gsm-network (at+creg), if the modem isn't registered on the modem and you fire the command that it should tell you that it has registered (unsolicited
result), then Telit modem sometimes shutdown completely and you need to
power it off/on to get it back to work. There are other circumstances when it crashed and you need to power off/on. But when you get the timing right it will work. Then we implemented the SMTP-Protocol (using the Indy stack) because we
needed some extra functionality. The problem there is, that the modem will work fine, but in the middle of the transmission it will send a break signal and crashed, we weren't able to find out why and how to prevent it from crashing. We asked Telit but they weren't able to reproduce the problem. So we hadn't a solution for 6 months.
After waiting for Telit we decided to try a different vendor. So we tried SonyEricssons GM29. No timing problems there but a major bug in the TCP/IP stack. It will not send a TCPIP datapackage if it is smaller
than 300 bytes. There is no way telling the modem to send a small IP telegram. SE service was very friendly, they can reproduce the problem but we are now waiting for 4 weeks and no fix available. They also told
us that the gm29 will be discontinued and the followup product isn't available yet.
So we tested the wavecom fastrack M1306B. And here we are, modem works find, no timing problems, the IP-Stack works as well, we are able to send huge EMails. In addition the commandset is much bigger than Telit's or SEs and there is useful description and examples. At the moment we are testing more functions and it looks good.
This is a real experience report, we are not on the wavecom payroll !
if you like to contact us please feel free to send us an EMail: snipped-for-privacy@connective.biz. we would be happy to help or to discuss some issues.
Kind regards Ruediger