VHX-1420 VESDA Metal Box HLI Modbus Type 3VESDA Modbus Type 3 High Level Interface The VESDA Modbus Type 3 High Level Interface (HLI) integrates VESDAnet1 network with host monitoring platforms such as Building Management Systems (BMSs) and Fire Alarm Control Panels (FACPs). The Modbus Type 3 HLI acts as a proxy for all VESDA devices on the VESDAnet network, providing access to the rich status information that is available from VESDA detectors as well as the ability to control and configure