Chapter 3 Features and Functions
Outputs
ALARM/STATUS Port Inputs
The input pins (6 and 7) of this port are shown in Figure
ALARM/STATUS
1 2 3 4 5
6 7 8 9
Alarm Inputs
Figure 3-2. Alarm Inputs
Always connect the input A input device to pin 6 of the ALARM/STATUS connector, and connect the input B input device to pin 7. Do NOT use or ground pin 8.
When an alarm input from the device connected to input A is received by the 58502A, the 58502A switches to using the backup signal (input B) as the source signal, and automatically reflects the alarm in its own alarm outputs and routes this information to pin 6 of the ALARM/STATUS connector. Conversely, similar actions occur when an alarm input from the device connected to input B is received by the 58502A, except the alarm information is routed to pin 7 of the ALARM/STATUS connector.
The INP:ALARM? query returns the alarm status of frequency sources connected to pins 6 and 7. See Chapter 4, “Command Reference,” for details on this query.
The following paragraphs provide an example on how the alarm system works.
Let’s say you connected the HP 5071A Primary Frequency Standard signal to input A, and connected the 58503A GPS Receiver signal to input B. Then you connected the HP 5071A status output to pin 6 of the ALARM/STATUS port, and the 58503A alarm output to pin 7. (The common or return for these signals should be connected to pin 9, ground. You need to make a special cable for these connections.)
If the HP 5071A fails and sends an alarm, the 58502A will automatically switch to the backup input signal from the 58503A on input B. Using INP:ALARM? query would return 1,0,0, indicating that the alarm occurred in the device connected to pin 6.
User’s Guide |