The SNAP-AIV-4 is a 4-channel analog voltage input module for use with Opto22 SNAP PAC systems. Although the four channels are not isolated from each other, the module is transformer isolated and optically isolated from other modules and devices. Part of the SNAP PAC System, the module mounts on a SNAP PAC rack with a SNAP PAC brain or rack-mounted controller. Analog, digital and serial I/O modules can all be on the same rack. Such an I/O unit is also well suited for PC-based control or for use as intelligent remote I/O for an Allen-Bradley RSLogix PLC system, such as ControlLogix, MicroLogix or CompactLogix.