GE B90 Instruction Manual page 267

CHAPTER 5: SETTINGS
Figure 5-51: Dual-channel closed loop (dual-ring) configuration
In 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 cycle
IED 1 to IED 3: 0.2 of power system cycle
IED 2 to IED 3: 0.2 of power system cycle
The two communications configurations can be applied to both permissive and blocking schemes. Take speed, reliability,
and cost into account when selecting the required architecture.
5.3.16.2 CRC alarm CH1(2)
SETTINGS  PRODUCT SETUP  DIRECT I/O  CRC ALARM CH1(2)
 CRC ALARM CH1

The B90 checks integrity of the incoming direct input and output messages using a 32-bit CRC. The CRC alarm function is
available for monitoring the communication medium noise by tracking the rate of messages failing the CRC check. The
monitoring function counts all incoming messages, including messages that failed the CRC check. A separate counter
adds up messages that failed the CRC check. When the failed CRC counter reaches the user-defined level specified by the
setting within the user-defined message count
CRC ALARM CH1 THRESHOLD
FlexLogic operand is set.
When the total message counter reaches the user-defined maximum specified by the
setting, both the counters reset and the monitoring process is restarted.
B90 LOW IMPEDANCE BUS DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
CRC ALARM CH1

FUNCTION: Disabled
CRC ALARM CH1

MESSAGE COUNT: 600
CRC ALARM CH1

THRESHOLD: 10
CRC ALARM CH1

EVENTS: Disabled
Range: Enabled, Disabled
Range: 100 to 10000 in steps of 1
Range: 1 to 1000 in steps of 1
Range: Enabled, Disabled
, the
CRC ALARM 1 CH1 COUNT
CRC ALARM CH1 MESSAGE COUNT
PRODUCT SETUP
5
DIR IO CH1 CRC ALARM
5-111