... sensors. USB port: plug and play. Support 1GB,2GB,..USB flash driveCommunication: RS485,RS232, MODBUS-RTU protocolPrint:RS232, connecting mini printer Record timeRecord interval can be set optionally ... ………180days…….10800daysPower-off protection timeThe setting parameters and history record can be kept byFLASH MEMORY, which can be kept forever when the power is off ...