GE Multilin G30 Generator Protection System 2-92 PRODUCT DESCRIPTION 2.1 INTRODUCTION2The UR automatically detects whether an authentication request is to be handled remotely or locally. As there are only fivelocal accounts possible on the UR, if the user ID credential does not match one of the five local accounts, the UR automat-ically forwards the request to a RADIUS server when one is provided.If a RADIUS server is provided, but is unreachable over the network, server authentication requests are denied. In this situ-ation, use local UR accounts to gain access to the UR system.2.1.3 IEC 870-5-103 PROTOCOLIEC 870-5-103 is a companion standard to IEC 870-5 suit of standards for transmission protocols. It defines messages andprocedures for interoperability between protection equipment and devices of a control system in a substation for communi-cating on a serial line.The IEC 60870-5-103 is an unbalanced (master-slave) protocol for coded-bit serial communication, exchanging informationwith a control system. In the context of this protocol, the protection equipment is the slave and the control system is themaster. The communication is based on a point to point principle. The master must be able to interpret the IEC 60870-5-103 communication messages.The UR implementation of IEC 60870-5-103 consists of the following functions:• Report binary inputs• Report analog values (measurands)• Commands• Time synchronizationThe RS485 port supports IEC 60870-5-103.
