gprs gsm modem 1.850/900/1800/1900MHZ 2. rs232/rs485/TTL 3.remote control through gprs ... two channels IO output. Remote control and reading. Alarmstatus threshold, automatic alarm signal report ... function Strong server software support, application for many years, strong function. Supply DTU ... and small size, low cost, easy to be embedded integration Industrial class design and components ...