Black Box 5000 - Manual (Page 246)

Multiserver 5000
244
LL RT SI RD TD
Figure E-5. CSU/DSU Module Indicator Positions.
LED Indicator
Indicator Definition Off Flashing On
LL Local Loopback Normal operation Local Loopback Test ---
is active
RT Remote Terminal Normal operation Digital Loopback or Remote ---
Terminal Loopback Test is
active
SI Status Indicator Power is off or CSU/DSU is receiving Power is on and
module is defective out-of-service signals from CSU/DSU is
code, or out-of-frame DDS synchronized with
code, or no DDS signal the network
is being passed
RD Received Data No data is being CSU/DSU module is CSU/DSU module
received by the receiving error during is receiving data
CSU/DSU module Test Pattern Test
TD Transmitted Data Not data is being Data is being Data is being
Table E-5. CSU/DSU Module Indicators