Siemens 2000592-001 ユーザーズマニュアル

Continued 

 

If the ANCB_DN port LED is never green, or intermittently flashes 
between green and red, there may be a signal quality problem. Signal 
levels should be examined to determine if a particular port has a signal 
too large or too small relative to the other ports on the HUB. If a link fails 
to connect at all, place the port in a test mode which will cause activity to 
occur every ~50 milliseconds instead of every ~5 seconds as on an 
unconnected link.  

To place the unit in a test mode use the CLI commands to take the link 
offline (port stop n) and initiate the test mode (test n). At this time, an 
oscilloscope may be taken to the site of the slave device and connected 
to monitor the signal. The signal received at the slave should be between 
~0.75 v p-p and 5 v p-p. A signal smaller than ~0.75 v p-p is generally 
not adequate. The impedance matching jumpers can be changed to 
correct some signal level issues.  

If the condition of excessive signal loss can not be corrected by jumper 
settings, it may indicate inadequate cable properties (i.e. too long or 
wrong type of cable). 

The port can be taken off test mode and put back to normal operation 
with the “test off” and “port start n” commands. 

 

•  Troubleshooting