... High, Low limit alarm(Option)Can select 4-20mA,0-10mA signal retransmission output(Option)Can select RS485 ... limitsCommunication : RS485 or RS232 ,MODBUS-RTU protocol, Or 4-20mA,0-10mAKeyboard : 4 keysScaling : -999 to 9999Mounting method ... ammeter, voltmeter, current meter, voltage meter, power meter, pannel meter, ohmmeter, high-impendence ohmmeter DP4-RMS Intelligent Digital DC/AC Ammeter/Volmeter