Variable-level integrity checks for communications in process control environments

A system for transmitting messages including values for process variables that can be authenticated at the parameter level, the system comprising:

• a first process control device configured to be communicatively coupled to one or more other process control devices in an input/output (I/O) network of a process control environment for controlling a process, the first process control device including:
• (A) a communication interface configured to couple the field device to the one or more controllers;
• and
• (B) a set of circuits communicatively coupled to the communication interface and configured to:
• detect a detected value for a device variable;
• calculate a first data integrity check by way of performing a data integrity calculation using the detected value and a seed as inputs;
• encode a message to include the detected value and the first data integrity check for the detected value;
• and
• transmit, via the communication interface, the message to a second process control device that is configured to:
• (i) receive the message, (ii) calculate a second data integrity check for a candidate value in the message for the device variable;
• (iii) update or not update, at the second process control device, a process variable mapped to the device variable with the candidate value based on whether or not the first and second data integrity checks match;
• and (iv) implement a function as part of a control scheme for the process in accordance with the process variable.

A method for verifying the integrity of device variable values included in a message from a process control device, the method comprising

• receiving a message, transmitted by a first process control device, at a second process control device in a process control environment for controlling a process;
• decoding the message to identify within the message:
• (i) a candidate value for a device variable, and (ii) a first data integrity check for the device variable;
• calculating a second data integrity check by way of a performing a second data integrity calculation using the candidate value and a seed as inputs;
• comparing the second data integrity check to the first data integrity check to determine whether or not the second data integrity check matches the first data integrity check and to thereby determine whether or not the candidate value matches a detected value that was used to calculate the first data integrity check;
• responding to determining that the second data integrity check does not match the first data integrity check by discarding the candidate value such that a process variable mapped to the device variable maintains a prior value;
• responding to determining that the second data integrity check matches the first data integrity check by updating, at the second process control device, the process variable with the candidate value;
• and
• implementing, in accordance with the process variable, a function as part of a control scheme for the process.

A system for verifying the integrity of device variable values included in a message from a process control device, the system comprising:

• a second process control device configured to be communicatively coupled to a first process control device in a process control environment, the second process control device including:
• (A) a communication interface configured to communicatively couple the second process control device to the first process control device;
• and
• (B) a set of circuits communicatively coupled to the communication interface and configured to:
• receive, via the communication interface, a message transmitted by the first process control device;
• decode the message to identify within the message:
• (i) a candidate value for a device variable, and (ii) a first data integrity check for the device variable;
• calculate a second data integrity check by way of a performing a second data integrity calculation using the candidate value and a seed as inputs;
• compare the second data integrity check to the first data integrity check to determine whether or not the second data integrity check matches the first data integrity check and to thereby determine whether or not the candidate value matches a detected value that was used to calculate the first data integrity check;
• respond to determining that the second data integrity check does not match the first data integrity check by discarding the candidate value such that a process variable mapped to the device variable maintains a prior value;
• respond to determining that the second data integrity check matches the first data integrity check by updating the process variable with the candidate value;
• and
• implement, in accordance with the process variable, a function as part of a control scheme for the process.