This is a PC RS-232 or RS-485 switchable Computer Interface Card Module with 4 setpoint relays for field installation on MKS Granville Phillips Series 350 Controllers with 3 Line Digital Displays. The PC/RS-232/RS-485 interface for the controller allows data output to, and gauge control by, a host computer. Output is by a command-response mechanism. Process control features of this module provide the controller with 4 single-pole, double-throw relays that may be controlled either by 4 digital front panel LED indicator setpoints or by the built-in manual override switches. See Chapter 6, Page 55 of .pdf manual for instructions on use of the RS-232/RS-485 Module. This is the RS-232/RS-485 Computer Interface Card Module ONLY, MKS Granville Phillips 350 Controller, Cables and Accessories sold separately on this website. The MKS Granville Phillips 350 Vacuum Gauge Controller Instruction Manual can be downloaded below at DOWNLOADS: