Datasheet

DS21Q50
29 of 87
4.3 Automatic Alarm Generation
The device can be programmed to automatically transmit AIS or remote alarm. When automatic AIS
generation is enabled (CCR2.5 = 1), the device monitors the receive framer to determine if any of the
following conditions are present: loss of receive frame synchronization, AIS alarm (all ones) reception, or
loss-of-receive carrier (or signal). If any one (or more) of the above conditions is present, then the framer
forces an AIS alarm.
When automatic RAI generation is enabled (CCR2.4 = 1), the framer monitors the receive to determine if
any of the following conditions are present: loss-of-receive frame synchronization, AIS alarm (all ones)
reception, or loss-of-receive carrier (or signal), or if CRC4 multiframe synchronization cannot be found
within 128ms of FAS synchronization (if CRC4 is enabled). If any one (or more) of the above conditions
is present, the framer transmits an RAI alarm. RAI generation conforms to ETS 300 011 specifications
and a constant remote alarm is transmitted if the DS21Q50 cannot find CRC4 multiframe synchronization
within 400ms as per G.706.
Register Name:
CCR3
Register Description:
Common Control Register
Register Address:
14 Hex
Bit 7 6 5 4 3 2 1 0
Name RLB LLB LIAIS TCM4 TCM3 TCM2 TCM1 TCM0
NAME BIT FUNCTION
RLB 7
Remote Loopback. See Section 4.4
for details.
0 = loopback disabled
1 = loopback enabled
LLB 6
Local Loopback. See Section 4.5
for details.
0 = loopback disabled
1 = loopback enabled
LIAIS 5
Line Interface AIS Generation Enable
0 = allow normal data to be transmitted at TTIP and TRING
1 = force unframed all ones to be transmitted at TTIP and TRING at the MCLK rate
TCM4 4
Transmit Channel Monitor Bit 4. MSB of a channel decode that determines which transmit
channel data appear in the TDS0M register. See Section 6
or details.
TCM3 3 Transmit Channel Monitor Bit 3
TCM2 2 Transmit Channel Monitor Bit 2
TCM1 1 Transmit Channel Monitor Bit 1
TCM0 0 Transmit Channel Monitor Bit 0. LSB of the channel decode.