A test system (10) is coupled to a control system (20) in a manner
which allows the test system to communicate with and drive the control system by
sending and receiving signals via both the controller-I/O communication channel
(160) and the field I/O connectors (225). The test system (10)
is used to both simulate a plant to be controlled and to monitor, validate, and/or
modify the internal state of the control system controller and possibly the control
system I/O interface (220). Plant simulation is accomplished by simulating
the I/O devices to which the control system (20) is coupled (and hence the
plant processes) when installed in the operational environment. In addition to
the simulation of I/O devices, the test system (10) takes advantage of the
fact that many commonly used controller and I/O interfaces are capable of communication
with other devices by using such communications ability to provide instructions
to or obtain information from a control system's controller(s) and I/O interface(s).
