Alarm Detection: The status of the Red alarm, Yellow alarm and Blue alarm are indicated by the corresponding status bit. T1/J1 Alarm Status register keeps a static status of Red, Yellow and Blue alarms. T1/J1 Alarm Indication register will be logged whenever there is a status transition change (from “0” to “1” or from “1” to “0”) of T1/J1 Alarm Status bits. T1/J1 Alarm Control register controls whether any of the alarms will initiate an interrupt. In addition, for each of the three types of alarms, there are Declare and Clear Threshold registers which configure the threshold for these alarms to be declared or cleared.
Alarm Generation:
• Generation of AIS – upon LOS, the port will automatically transmit an unframed all ones' data pattern, if so configured.
• Generation of LOS – if received signal meets corresponding standards, the receiver will declare Loss of Signal (LOS) alarm
indicated by both internal status register bits and dedicated pin.
• Generation of LOF – Red alarm includes both LOS and LOF. LOS is described above. If received data stream loses framing
pattern threshold, LOF will be indicated by status registers.
• Generation of RAI – RAI is transmitted by transmitting the 16-bit pattern “1111111100000000” in its data link bit.
Refer to application note AN-856 for more details. For other questions not addressed by the Knowledge Base, please submit a technical support request.


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Application Notes & White Papers
AN-856 IDT Transceivers Handling of T1/E1/J1 Signaling,Alarms and Errors Application Note PDF 197 KB