A control system for technical installations includes at least one electronic manual operator-control instrument that can be carried and used mobilely by an operator-control person for influencing and observation of the control system or a connected technical installation. The instrument has a wireless communication interface and a communication interface established via a connecting cable. At least one safety switching element actuated by the person on the manual operator-control instrument can at least terminate potentially hazardous control commands or movement sequences. The hard-wired communication interface includes a contact-based plug interface on the instrument having a first coupling element on the instrument and a second coupling element coupled and decoupled as needed relative to the first coupling element. At least one termination indicator on or in the connecting cable directly in or near the second coupling element can be sensed electronically by a termination-indicator detector.

An information processing device includes: a detection unit configured to detect an event generated in a control system including at least one network; a connection configuration expression unit configured to visually express a physical connection and a logical connection of the network included in the control system; and an event output unit configured to output the event detected by the detection unit while correlating the event with the physical connection and the logical connection of the network, the physical connection and the logical connection being visually expressed according to a place where the event is generated.

A handheld maintenance tool operates to detect the existence of a fault in a communication line or bus, including detecting short circuit or other low impedance faults, open circuit or other high impedance faults, etc. Additionally, the handheld maintenance tool may operate to detect an approximate location of a fault within the communication line with respect to the handheld device, to thereby enable an operator or maintenance person to more easily find and repair a detected fault.