... (Optional GPRS modem 3G modem M2M GPRS Modem With RS232 RS485 for Meter Reading Temperature and Humidity Monitoring (F2103I ... TCP/IP stack, supports transparent data transmission, AT Command, RS232/485, remote configuration and control, with embedded Operation System, such ... Hardware System 1. MCU High-powered MCU, 100M 2.Interface RS232/RS485 serial port, rates: 110~230400bits/s Indicator lights: ...