Phenomenon Description

The OSN 3500 device has no alarm, but the alarm sound of the column header cabinet keeps ringing, and the alarm sound stops when the alarm output cable of the OSN 3500 device is unplugged on the column header cabinet.

Cause Analysis

When the alarm input cable is unplugged from the header cabinet, the alarm sound on the header cabinet is cleared, and it can be localized that the fault belongs to the alarm output of the OSN 3500 device; it is not the fault of the header cabinet itself.

Procedure

The fault location is the alarm output of OSN 3500, and the alarm output line is connected to the ALMO1 port of the AUX single board. Query the ALMO1 port for the alarm output pin definitions as follows:

Pin 1 Emergency and Major Alarm Signal Output Positive

Pin 2 Emergency and major alarm signal output negative

Pin 3 Positive general and reminder alarm signal output

Pin 6 Negative general and alert alarm signal output

To artificially cause the device to generate an RLOS emergency alarm, test the electrical indicators between pin 1 and pin 2. Tested DC voltage to 0, AC voltage to 0, tested resistance and found resistance to be :53.6 ohms;

Mask the RLOS alarm on the device, there is no emergency alarm on the network element, retest, test DC voltage is 0, AC voltage is 0, test resistance, resistance is 53.6 ohms, electrical indicators do not have any change. Cannot determine the cause of the failure;

Retest the other 1OSN 3500 device in the server room, and find that there is a change in the indicators of the alarm output port of the AUX single board, when the device generates an emergency alarm, the resistance between pin 1 and pin 2 is 53.6 ohms, and when the device does not have an alarm, the resistance is infinite; the voltage indicator is 0, and there is no voltage;

Thus, it is judged that the working principle of the alarm output port of the OSN 3500 device AUX single board is the same as that of the alarm output port of the 2500+. The alarm output is a switching state of the port. There is no voltage.

From the above procedure, we can see that the abnormality of the AUX board of the OSN 3500 device causes the alarm output port state to be unanimously in the closed state, causing the header cabinet alarm. After replacing the AUX board, the test is normal.

Recommendation Summary

In the OSN3500 hardware description, do not misunderstand the definition of ALMO1 and ALMO2 pins of the alarm output port of the AUX single board, as the alarm output port does not have any voltage. When a network element generates an alarm, the port resistance is 53.6 ohms, and when the network element does not generate an alarm, the port resistance is infinite .

Alarm output port, the output is switching state. Closed Loop and Disconnected . For similar faults of NGSDH products, we hope that this case can have a helpful role for you.