Rockwell Automation DeviceNet System Quick Reference - Manual (Page 13)

DeviceNet System Quick Reference
DNET-QR001A-EN-E – March 2009 13
Maintain
Diagnostics and Troubleshooting
The 193-DNCT terminal has some diagnostics built in that can be used to troubleshoot a DeviceNet
network. These diagnostics include bus voltages, bandwidth utilization percentage, and CAN error
counts.
1. Press the Down Arrow to navigate to Node 62 This DeviceNet HIM.
2. Press Enter to select the HIM.
3. Press the Down Arrow to navigate to and select the Network group and press Enter .
This dialog box, with similar values, appears on the 193-DNCT terminal.
The Max Bus % Load and CAN Errors/Sec parameters are not easily measured by other means
and are valuable for troubleshooting the network. The Max Bus % Load parameter shows the
maximum network bandwidth that has ever been used. If this value goes too high, communication
anomalies could occur on the network due to devices being ‘starved’ for bandwidth. The CAN
Errors/Sec parameter is generated if packets are being corrupted on the network, such as due to
electrical noise or a bad device. This value, which should be zero on a healthy network, is a good
barometer of the general health of the DeviceNet packet-delivery mechanism.
Baud Rate: 125K
Bus Voltage: 23.90
Bus Voltage Hi: 24.02
Bus Voltage Low: 23.81
Bus % Load: 9.4
Max Bus % Load 16.9
CAN Errors/Sec: 0