摘要 |
A process control system includes a processor which outputs command signals to a plurality of field devices via an interface unit. The interface unit comprises a primary output unit for outputting a first set of the command signals to the field devices in response to a first control signal. The first set of command signals are command signals for normal operation of the process control system. A secondary output unit outputs a second set of the command signals to the field devices in response to a second control signal. The second set of command signals are command signals for a failure mode of operation of the process control system. The second set of command signals are temporarily stored by the secondary output unit in order to respond quickly upon detection of an error.
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