Control system upgrade for the DIII-D neutral beamline

After a decade of operation, the DIII-D tokamak neutral beamline control system has been upgraded using a medium-sized programmable logic controller (PLC). Its primary function is direct and automatic control of the vacuum, gas, and water-cooling systems. The control instrumentation (CI) PLC provides an interface to the main beam control computer and other local control devices. The PLC features high-density, optically isolated inputs and outputs and intelligent analog input/output (I/O). The PLC is concentrated in the CI station located near the neutral beamline tank. Remote, online, optically isolated programming and diagnostics are achieved through the use of inexpensive RS232C modems and a central programming station. Independent, peer, or hierarchical operation, future graphics capability on a fast network, and expansion capability were goals of this design change. Automation, enhanced capability, and flexibility of control are discussed