Overview
The Vapor-logic4 controller provides comprehensive control for DRI-STEEM humidifiers.

Features
Interoperability allows communication with building automation systems via Modbus or with optional BACnet MS/TP or LonTalk protocols.
Web interface provides the capability to set up, view, and adjust humidifier functions via Ethernet, either directly or remotely through a network.
USB port allows easy firmware updates, and data backup and restore capability.
PID control allows tuning of the system for maximum performance.
Real-time clock allows time-stamped alarm and message tracking, and accurate drain and flush scheduling.
Programmable outputs allow remote signaling and device activation.
Enhanced diagnostics include a test outputs  function to verify component operation, and a  test humidifier function to simulate humidifier  demand to validate performance.
Auxiliary temperature sensor/transmitter allows air temperature monitoring, such as in a duct, and enables temperature compensation to prevent window condensation (not available for XT humidifiers).

From http://www.dristeem.com/products_ControllersAcess_VL4.jsp