The SCC-300-PRG/SCC-310-PRG programmable space comfort controller allows integrators to implement tailored control applications for unique or custom terminal unit designs when configurable-only application-specific controllers do not meet their needs, while still meeting requirements for a cost-effective controller that is LonMark® certified. The SCC-300-PRG/SCC-310-PRG accepts the download of a Circon BASIC program to provide a device application tailoring the sequences of operation for the terminal unit being controlled. Program development is very simple, using the Circon BASIC language and compiler to develop and download the program. Many built-in procedures are included to enhance the ease of program development for programmable space comfort controllers and to enable conformance to the LonMark standard functional profile by allowing programmatic access to read and write mandatory network variables and configuration properties. The SCC-300-PRG/SCC-310-PRG works with the LNS® operating system and is supplied with LNS plug-ins to simplify configuration of built-in I/O, scheduler, PID, optimum start, trending, alarming, and type-changeable network variables functional blocks.