CHAPTER 5: SETTINGS PRODUCT SETUPB90 LOW IMPEDANCE BUS DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL 5-1275Figure 5-61: Dual-channel closed loop (dual-ring) configurationIn this application, apply the following settings. For UR-series IED 1:DIRECT OUTPUT DEVICE ID: “1”DIRECT I/O CH1 RING CONFIGURATION: “Yes”DIRECT I/O CH2 RING CONFIGURATION: “Yes”For UR-series IED 2:DIRECT OUTPUT DEVICE ID: “2”DIRECT I/O CH1 RING CONFIGURATION: “Yes”DIRECT I/O CH2 RING CONFIGURATION: “Yes”For UR-series IED 3:DIRECT OUTPUT DEVICE ID: “3”DIRECT I/O CH1 RING CONFIGURATION: “Yes”DIRECT I/O CH2 RING CONFIGURATION: “Yes”In this configuration the following delivery times are expected (at 128 kbps) if both the rings are healthy:IED 1 to IED 2: 0.2 of power system cycleIED 1 to IED 3: 0.2 of power system cycleIED 2 to IED 3: 0.2 of power system cycleThe two communications configurations can be applied to both permissive and blocking schemes. Take speed, reliability,and cost into account when selecting the required architecture.5.3.17.2 CRC alarm CH1(2)SETTINGS PRODUCT SETUP DIRECT I/O CRC ALARM CH1(2)The B90 checks integrity of the incoming direct input and output messages using a 32-bit CRC. The CRC alarm function isavailable for monitoring the communication medium noise by tracking the rate of messages failing the CRC check. Themonitoring function counts all incoming messages, including messages that failed the CRC check. A separate counteradds up messages that failed the CRC check. When the failed CRC counter reaches the user-defined level specified by theCRC ALARM CH1 THRESHOLD setting within the user-defined message count CRC ALARM 1 CH1 COUNT, the DIR IO CH1 CRC ALARMFlexLogic operand is set.When the total message counter reaches the user-defined maximum specified by the CRC ALARM CH1 MESSAGE COUNTsetting, both the counters reset and the monitoring process is restarted. CRC ALARM CH1 CRC ALARM CH1FUNCTION: DisabledRange: Enabled, Disabled CRC ALARM CH1MESSAGE COUNT: 600Range: 100 to 10000 in steps of 1 CRC ALARM CH1THRESHOLD: 10Range: 1 to 1000 in steps of 1 CRC ALARM CH1EVENTS: DisabledRange: Enabled, Disabled
