A problem investigating device for a process control system , the device comprising: a system model comprising software representations of process control endpoint devices interconnected via a communication network using a number of links, where each link (L1) is provided for communication in relation to a process control function between two endpoint devices and comprises a set of communication network elements (CM1, CM2, CM3, 20, 48) and a reference to a set of communication parameters of the process control function, where at least one communication network element references the communication parameters, and a root cause analysing unit configured to: - obtain an indication that at least one communication parameter deviates from a corresponding communication requirement (CR), - identify a link where reference is made to the communication parameter, - identify the communication network elements contributing to the functioning of the link, - indicate at least one of the communication network elements as a possible cause of the deviation based on the communication network element identification, and wherein the root cause analysing unit is further configured to: - rank the communication network elements according to the probability of being the cause of the deviation, and/or - indicate criticality associated with the network element(s) when indicating at least one of the communication network elements as a possible cause of the deviation. a system model comprising software representations of process control endpoint devices interconnected via a communication network using a number of links, where each link (L1) is provided for communication in relation to a process control function between two endpoint devices and comprises a set of communication network elements (CM1, CM2, CM3, 20, 48) and a reference to a set of communication parameters of the process control function, where at least one communication network element references the communication parameters, and a root cause analysing unit configured to: - obtain an indication that at least one communication parameter deviates from a corresponding communication requirement (CR), - identify a link where reference is made to the communication parameter, - identify the communication network elements contributing to the functioning of the link, - indicate at least one of the communication network elements as a possible cause of the deviation based on the communication network element identification, and wherein the root cause analysing unit is further configured to: - rank the communication network elements according to the probability of being the cause of the deviation, and/or - indicate criticality associated with the network element(s) when indicating at least one of the communication network elements as a possible cause of the deviation. - obtain an indication that at least one communication parameter deviates from a corresponding communication requirement (CR), - identify a link where reference is made to the communication parameter, - identify the communication network elements contributing to the functioning of the link, - indicate at least one of the communication network elements as a possible cause of the deviation based on the communication network element identification, and wherein the root cause analysing unit is further configured to: - rank the communication network elements according to the probability of being the cause of the deviation, and/or - indicate criticality associated with the network element(s) when indicating at least one of the communication network elements as a possible cause of the deviation. - rank the communication network elements according to the probability of being the cause of the deviation, and/or - indicate criticality associated with the network element(s) when indicating at least one of the communication network elements as a possible cause of the deviation. <EOS>