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.GUID-8C333BC0-AA7A-4ED1-A772-18C22E8EEE62 v5When CHNGLCK has a logical one on its input, then all attempts tomodify the IED configuration and setting will be denied and themessage "Error: Changes blocked" will be displayed on the local HMI;in PCM600 the message will be "Operation denied by activeChangeLock". The CHNGLCK function should be configured so that itis controlled by a signal from a binary input card. This guarantees thatby setting that signal to a logical zero, CHNGLCK is deactivated. Ifany logic is included in the signal path to the CHNGLCK input, thatlogic must be designed so that it cannot permanently issue a logical oneto the CHNGLCK input. If such a situation would occur in spite ofthese precautions, then please contact the local ABB representative forremedial action.23.4 Denial of service SCHLCCH/RCHLCCH23.4.1 Application GUID-64F4D905-9F73-4073-B8F6-8D373155316A v5The denial of service functionality is designed to limit the CPU load that can beproduced by Ethernet network traffic on the IED. The communication facilities mustnot be allowed to compromise the primary functionality of the device. All inboundnetwork traffic will be quota controlled so that too heavy network loads can becontrolled. Heavy network load might for instance be the result of malfunctioningequipment 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:1MRK 504 163-UUS A Section 23SecurityTransformer protection RET670 2.2 ANSI 961Application manual
