I am using the GM862-GSM/GPRS with RS-EB-S1 board.
Why does it go down into sleep mode after 20-30 Sek?
The interface chip MAX3238E on the RS-EB-S1 board has an Auto-Power-Down Mode.
This chip has an automatic power-down mode (after 20-30 Sek) to reduce the power consumption.
You can switch this mode off when you lift up the Pin number 13 of the MAX3238E, so that he has no more contact to Ground and
then connect it to pin 14 of the MAX3238, that means to VCC.
After this patch the chip never will switch to the auto-power-down mode.
If you wish to obtain the data sheet of the MAX3238E, please contact Rround Solutions.
We are happy to help you!