Rockwell Automation 1788-CNCHKR ControlNet NetChecker User Manual - Manual (Page 10)

10 ControlNet NetChecker
Rockwell Automation Publication 1788-UM001B-EN-P - August 2012
Bargraph Scale
The Bargraph is not a precision voltmeter. The status indicators are numbered from 1 (lowest
peak-to-peak voltage or Vpp) to 7 (highest Vpp). Also note that the scale is not linear. The
following table shows the approximate peak-to-peak voltages indicated by each status indicator.
Status indicator 7 will turn red if the signal level exceeds 9.5Vpp. Otherwise, it will be off. Status
indicator 1 can have one of three states: red if the signal input is less than 0.75Vpp, green if the
signal input is between 0.75 and 2Vpp, and off under any other condition. Status indicators 2…6
can only be green or off.
Only two status indicators on the bargraph can be turned on at the same time, one indicating the
maximum level and the other indicating the minimum. If the maximum and the minimum levels
are the same, only one status indicator will turn on.
View a Node Signal Level in Bargraph Mode
To check the signal level from a particular node, set SW3 to the rightmost position and set the
address of the node on the Node Finder thumbwheels. Note that the bargraph indication is the
level seen at the point of test, so a low or high indication does not necessarily mean that the node
itself is faulty. If all of the status indicators are off, the NetChecker does not detect any signal
from a node having the address entered.
Perform a Global Survey of Signal Levels
To perform a global survey of the signal levels of all messages on a network, set SW3 to its
rightmost position and set the Node Finder thumbwheels to 00. The NetChecker will display
two green status indicators, indicating the strongest and the weakest levels encountered on the
network. The maximum and the minimum levels indicated remain latched until NetChecker
power is cycled.
Status Indicator Vpp Level Status Indicator GREEN if Status Indicator RED if
7 9.5 No green state Signal level > 9.5Vpp
6 7.5 7.5Vpp < signal level < 9.5Vpp No red state
5 5.75 5.75Vpp < signal level < 7.5Vpp
4 4.5 4.5Vpp < signal level < 5.75Vpp
3 3.25 3.25Vpp < signal level < 4.5Vpp
2 2 2Vpp < signal level < 3.25Vpp
1 0.75 0.75Vpp < signal level < 2Vpp Signal level < 0.75SVpp
IMPORTANT In networks in which repeaters are used, the level read on the bargraph for nodes that are
behind a repeater, such as on another trunk cable than the one being tested, is the level of
signal from the repeater.