The new 3G modules (or the serial interface) have the tendency to hang when using AT command to send SMS over serial.
I’ve been having to live with this problem since FX100 and now M100 3G that uses the SL80XXS. Increasing the interval between characters in the serial stream will helps to greatly reduce the likelihood of this happening but is not full proof and every 1000-10000 SMS sent will result in the module seizing up and stop responding to any AT command including AT+CFUN=1. Tried both HW and SW flow control.
This bug didn’t exist for earlier Wavecom modems like Supreme 20 which is ultra stable, you can throw anything at it, disconnect the serial port, it wouldn’t hang.
Is there a solution for this or is this a hardware defect in the newer modules? This bug has been around for years. I’ve tried upgrading to firmware R7.54, still no help. Thanks in advance.