A method and apparatus for providing an active standby control system comprising
the steps of providing a first and second programmable logic controller (PLC),
each controller having an operating state. Each controller further including a
network module board operably connected to a network; a control unit, a remote
I/O head; and, a hot standby module, each hot standby module is operably connected
together. Operably connecting each programmable logic controller to a network.
Assigning a network address identifier, i.e., Internet Protocol or Media Access
Control address, to each programmable logic controller and sensing the operating
state of each programmable logic controller. The network address identifier of
each programmable logic controller is determined by the operating state of each
respective programmable logic controller. The present invention is also directed
to an apparatus for communication with at least one device which resides on a standard
communications network using a standard communications protocol. The apparatus
has a scanner for scanning the device, a device scan table for storing data relating
to the device, and a standard communications interface for interfacing between
the device scanner and the standard communications network using the standard communication protocol.