The binary input controlling the function is defined in ACT or SMT. The CHNGLCKfunction is configured using ACT.LOCK Binary input signal that will activate/deactivate the function, defined in ACT or SMT.When CHNGLCK has a logical one on its input, then all attempts tomodify the IED configuration and setting will be denied and the message"Error: Changes blocked" will be displayed on the local HMI; in PCM600the message will be "Operation denied by active ChangeLock". TheCHNGLCK function should be configured so that it is controlled by asignal from a binary input card. This guarantees that by setting that signalto a logical zero, CHNGLCK is deactivated. If any logic is included in thesignal path to the CHNGLCK input, that logic must be designed so that itcannot permanently issue a logical one to the CHNGLCK input. If such asituation would occur in spite of these precautions, then please contact thelocal ABB representative for remedial action.23.4 Denial of service SCHLCCH/RCHLCCH23.4.1 ApplicationThe denial of service functionality is designed to limit the CPU load that can be producedby Ethernet network traffic on the IED. The communication facilities must not be allowedto compromise the primary functionality of the device. All inbound network traffic will bequota controlled so that too heavy network loads can be controlled. Heavy network loadmight for instance be the result of malfunctioning equipment connected to the network.The functions Access point diagnostics function block measure the IED load fromcommunication and, if necessary, limit it for not jeopardizing the IEDs control andprotection functionality due to high CPU load. The function has the following denial ofservice related outputs:• LINKSTS indicates the Ethernet link status for the rear ports (single communication)• CHALISTS and CHBLISTS indicates the Ethernet link status for the rear portschannel A and B (redundant communication)• LinkStatus indicates the Ethernet link status for the front port1MRK 506 369-UUS - Section 23SecurityLine distance protection REL670 2.2 ANSI 893Application manual
