[time-nuts] Z3816A Alarm light and Status

Rex rexa at sonic.net
Sat Jan 22 17:43:03 EST 2005


I posted the other thread here about my alarm light, which turned out to
be that my antenna was drawing too little current -- thanks for the
information that pointed me in the right direction.

While looking at that, it did puzzle me why I couldn't see any Alarm
indication in the status registers. Today I tried to understand more
about how the Alarm light works. Now it seems to me that all of the
description in the Z3801A and 58503B manuals don't seem to apply to the
Z3816A light. Mostly I used the 58503 manual as a reference. The
information in the 58503 manual about this stuff seems to be essentially
the same as the Z3801 manual, but with a little more detail in the
explanations. I thought I would share my investigation and see if anyone
has further information or comments.

I thought I would start by setting a User-reported status in the
Questionable register (:STAT:QUES:COND:USER SET). I expected this to
turn on the alarm light, but it didn't. 

Looking at the register(s) status, this is what I saw...

 :STAT:QUES:COND? = +2 = User-reported
 :STAT:QUES:ENAB? = +3 = User + Time Reset (enabled)
 *SRE? = +138 = 88h = Operational + Questionable (enabled)
 *STB? = +72 = 48h = Master Summary  + Questionable
 :LED:ALAR = 0 = off

Most of this matches what I expected from the documentation. According
to the manual the Alarm LED should be on. The STB value has the Master
Summary bit on which is supposed to be feedback from the alarm light.
The manual says the :LED:ALAR command reads the Master Summary bit. By
inspection, it doesn't on the Z3816, but it does read the status of the
actual light. (When I issued :LED:ALAR with the alarm light due to
antenna current yesterday, it returned  1 = on.)

So, to summarize my results, the Questionable and Alarm registers seem
to behave as documented in the Z3801 and 58503 manuals, but the light
doesn't follow the output of the OR after the Alarm register (Master
Summary does). Right now, it seems to me that the Alarm LED on the
Z3816A only reflects the status of the antenna current sense, or there
are some other undocumented controls that would allow gating the output
of the Alarm register to the LED.

Does anyone have any documentation for the Z3816A that would confirm,
supplement or contradict my observations?

Bill, K8CU, do you think I should post this on your BBS too?

-Rex





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