MDL4U001 is the mainframe controller for the MDL4U Series modular programmable DC electronic load system, designed to house and control up to 4 DC load modules. The mainframe features 4 slots that can be populated with any combination of modules up to 2400 W total power capacity, expandable to 4800 W with the MDL4U002 mainframe extension. It provides comprehensive communication interfaces including LAN, USB (USBTMC-compliant), RS232, and GPIB with SCPI protocol support for remote control. The mainframe operates on 110-220 V ± 10% at 50/60 Hz, with an operating temperature range of 32 to 104 °F (0 to 40 °C) and humidity up to 95%. Standard accessories include a power cord, USB cable, and certificate of calibration, making it ideal for testing multi-output DC power supplies, batteries, fuel cells, and photovoltaic arrays.