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Issue 4, August 2021 Model 5401A User Guide
Page 18 Studio Technologies, Inc.
Model 5401A
DANTE LEADER CLOCK
using its internal temperature-stabilized oscillator as
the failover timing reference. If Sync Input is displayed
this indicates that an external timing reference signal
is connected to the sync input BNC jack on the Model
5401A’s back panel and it is being used as the main
clock source. If Dante is displayed this indicates that
the Model 5401A is using a timing reference derived
from its Dante network interface. This is not an in-
valid condition but would typically only occur in a
troubleshooting situation. If Dante (Failover Active) is
displayed an abnormal condition is occurring. In this
case, the Model 5401A is using a timing reference
derived from its Dante network interface. However,
this is only occurring because the configured main
clock source is not currently available.
Sync Input Status: This is a display-only field with
choices of Locked (Active), Locked (Standby), Un-
locked, and Idle. As a warning of an abnormal condi-
tion the text Unlocked will display in the color red.
If Locked (Active) is displayed this indicates that a
valid signal is connected to the Model 5401A’s sync
input and is serving as the unit’s timing reference. If
Locked (Standby) is displayed this indicates that a
valid signal is connected to the Model 5401A’s sync
input and while it is capable of serving as the unit’s
main timing reference it is not currently serving as the
main clock source.
If Unlocked is displayed it can be the result of several
conditions. It can display if a signal is connected to
the Model 5401A’s sync input but is not being rec-
ognized as a valid timing reference. This can occur
for multiple reasons. The most common would be
due to a configuration mismatch, such as if a video
reference is connected while the Model 5401A’s sync
input is configured to support a word clock source. It
might also indicate that a non-supported word clock
rate or an incompatible video reference is connected.
Unlocked could also be displayed if no signal is con-
nected to the sync input or if a connected signal is
incorrectly terminated, e.g., no termination applied
when one is required or if two terminations (“a double
termination”) were present.
Idle will display if the sync input has not been selected
as the Model 5401A’s main clock source and a valid
source has not been connected to the sync input. It
simply indicates that the sync input circuitry is not
actively receiving an external signal.
Primary Leader Clock: A display-only field will show
the MAC (media access control) address of the Dante
network’s currently active Primary Leader Clock.
Displayed to the right of the MAC address will be an
additional piece of information about what specific
device is associated with the displayed MAC address.
If the MAC address is associated with this specific
Model 5401A then the text will show (This Device) . If
the MAC address is not for this specific Model 5401A
the text will show
(Other Device)
.
A logical question to ask would be “so what is this
Other Device?” Unfortunately, the Model 5401A’s
firmware does not have the ability to know more about
a specific Primary Leader Clock other than its MAC
address. It can only determine if the MAC address
matches this specific Model 5401A or not. If the ad-
dress doesn’t match then another device has to be
serving as the Primary Leader. The Dante Controller
may provide more detailed information about a Dante
network’s clocking. And network software or hardware
tools may allow a MAC address to be associated with
a specific device.
Note that the information provided in this field can be
a bit confusing, even to the writer of this guide. But for
a network maven it can be very useful when trouble-
shooting a complex network timing issue. Reviewing
several related issues to Primary Leader Clock can
be valuable. First of all, it’s important to note that the
reference to the word primary in “Primary Leader
Clock” has nothing to do with the primary and second-
ary Ethernet interfaces! In this context Primary Leader
Clock refers to the device that all other devices in a
Dante network will follow.
In most cases, a Model 5401A will serve as the Pri-
mary Leader Clock. But there is no requirement that
it must play this role. For example, a Model 5401A
can serve as a Leader Clock while following the tim-
ing provided by another device that’s serving as the
Primary Leader Clock. For another example, one
Model 5401A could serve as the Primary Leader Clock
while several other Model 5401A units serve as PTP
boundary clocks. These boundary clocks would, by
way of a unicast PTP message, synchronize with the
Primary Leader Clock. The boundary clocks could
then provide PTPv1 and PTPv2 functionality (using
multicast) with timing based on that derived from the
Primary Leader Clock. This method may be used to