Methods and apparatus for safety controls in industrial processes

A safety instrument suitable for use in an industrial application, said instrument comprising:

• a logic card including a microcontroller configured to perform self-test of said instrument and surveillance functions of an external system at least one of monitored or controlled by the instrument, and at least one complex programmable logic device (CPLD) configured to execute logic functions relating to human safety requirements of said external system independently of said microcontroller and to provide at least one of address decoding, input/output addressing, or registers for said microcontroller;
• one or more I/O modules operatively coupled to said logic card to communicate at least one of monitor signals or control signals from the logic card to the external system;
• and
• non-volatile RAM, and said microcontroller configured to store time-stamped error data in said non-volatile RAM.