RECEIVED ALARM CRITERIA Table 7-1
1) Receive carrier loss (RCL) is also known as loss of signal (LOS) or Red Alarm in T1.
2) See CCR1.5 for details.
SR (06H): STATUS REGISTER
Less than 2 zeros in two frames
Over a 3ms window, five or
fewer zeros are received
255 (or 2048)
192 (or 1544)
Loop Up Code Detected. Set when the loop up code defined in
registers RUPCD1 and RUPCD2 is being received. See Section
6 for details.
Loop Down Code Detected. Set when the loop down code
defined in registers RDNCD1 and RDNCD2 is being received.
See Section 6 for details.
Loss of Transmit Clock. Set when the TCLK pin has not
transitioned for 5msec (±2msec). Will force the LOTC pin high.
Receive Unframed All Ones. Set when an unframed all ones
code is received at RRING and RTIP. See Table 7-1for details.
Receive Carrier Loss. Set when a receive carrier loss condition
exists at RRING and RTIP. See Table 7-1for details.
Transmit Current Limit Exceeded. Set when the 50 mA (rms)
current limiter is activated whether the current limiter is enabled
Transmit Open Circuit Detect. Set when the device detects
that the TTIP and TRING outputs are open circuited.
PRBS Detect. Set when the receive-side detects a 2
or a 2
- 1 (T1) Pseudo Random Bit Sequence (PRBS).
35 of 73
More than 2 zeros in two frames
Over a 3ms window, six or more
zeros are received
In 255 bit times, at least 32 ones
14 or more ones out of 112
possible bit positions are
received starting with the first
- 1 (E1)