... modem, RS232 modem, GSM IP modem, GPRS data modem, data terminal,GPRS DTU, TCP/IP modem, Support transparent data transfe, gprs ip modem, gsm modemgprs modem ... same timeSupport multi online trigger ways, including SMS, ring and data. Support link disconnection when ... (Extendable)SRAM256KB(Extendable)Interface TypeItemContentSerial1 RS232 port and 1 RS485(orRS422) port, 15KV ESD protectionData bits: 5, ...