Digital valve positioner

A system for controlling a plurality of valves including a control computer, a plurality of programmable positioners and a communication link connecting the control computer and each of the programmable positioners, each valve associated with one of the programmable positioners, each programmable positioner comprising:

• a microprocessor having at least run and program modes,
• the microprocessor including a parameter memory for storing a plurality of programmable parameters including:
• Setpoint Direction,
• Output Current Range,
• Setpoint ramp--time to open, and
• Setpoint ramp--time to close,
• the microprocessor, in the run mode, executing a sequence of operations to control the position of the associated valve, and in the program mode executing a sequence of operations to respond to commands from the control computer, and received over the communication link, directing the storage of selected values in the parameter memory, and
• the microprocessor including means operating in the run mode for applying the values for the parameters of:
• Setpoint Direction,
• Output Current range,
• Setpoint ramp--time to open, and
• Setpoint ramp--time to close.