Dortronics Systems Inc. has released its 4900 Series Intelligent Interlock System for controlling mantraps and other customized applications. The programmable logic controller (PLC)-based system is factory-programmed with standard interlock configurations or can be customized for many operational requirements. Mantraps involve two sets of doors that surround a small space at the entrance of a facility. Typically, the first set of doors must be locked behind someone entering the facility before the second set of doors is opened. The modular design of the unit's Intelligent Interlock Processor enables control of any sized door interlock project.