Model:S271 Name: GSM 3G M2M RTU (4D+I4AI+4DO+1TH+1USB) The GSM 3G M2M RTU is a multi I/O port remote terminal unit. It is special for BTS monitoring, remote data acquisition, telemetrically, BTS access control and other applications. It supports voice communication, SMS, GPRS, 3G communications. Mainly Features: 1. ARM® Cortex™-M4 32 Bit RISC Core, 168 MHz inside, RTOS system; 2. Widely Rated voltage range, 9~36VDC, Inbuilt large capacity rechargeable backup battery; 3. Large internal memory for save 1000 historical data, USB port for configuration and upgrade firmware; 4. 4 analog inputs, 12bits, supports 0-5V, 0-20mA, 4-20mA; 5. 4 Relay outputs, 5A/30VDC,5A/250VAC; 6. 4 digital inputs, dry contact or level input. One of the input can be used as counter; 7. 1 temperature probe input, 1 humidity transducer input; 8. 2 IP data centers, supports Modbus TCP,TCP/IP protocol over GPRS/3G network; 9. Automatically resend the data while communication failure, GPRS failure will alert by SMS text; 10. Supports remotely restart the RTU, and configure it by SMS commands remotely; 11. Supports over voltage protection and phase-reversal protection; 12. 10 SMS Alert and auto dial numbers, can program to receive specified alarm message. 14. 10 access control authorized numbers, can open the BTS door or turn on/off machine with a free charge call at the specified time.