Baudcom BD-E1-ETH User's Reference Manual page 7

DIG: 10/100BASE-T Local loop-back, to check the opposite device and E1 circuit
REM: E1 interface loop-back outward to test E1 line
PATT: PBRS test. To produce and transmit the PBRS to the 10/100BASE input
connector, and to check whether the output signal of the 10/100BASE accord
with PBRS standard. If according, the PTOK light on, otherwise, off. By this
way, the status of E1 Line can be tested.
PBRS Code
REC & CHK
Push the PATT button, when loop circuit 1 is on, If PTOK is on , indicates device
works well ; loop circuit 1 off and loop circuit 2 on, indicates that fiber transmission
circuit and both side device work well
E1
Interfa
ce
When testing, one of above loop back must be on
E1 line
E1 LINE
Loop 1
7
Loop 2