Wegener Communications 6420 - Manual (Page 44)

iPump 6420 User’s Manual
www.wegener.com 800070-01 Rev B Chapter 3, Page 40
3.1. Monitor & Control Interfaces
3.1.1. Compel
The Compel control system is the premiere control method in the iPump 6420. It is the only
user control method that can overrule and lock out control from other sources. In particular, it
may set the edge devices, the remote iPump6420s, to have their local control disabled. This will
not disable all control capability, but it will essentially prevent the local user from changing the
unit settings in order to access some other audio programming. Once disabled by Compel, only
Compel itself, or a secured user with debugging access, or a unit that has reverted to Local
Control re-enable as part of unit Auto Recovery (see Section 3.1.8), can see it re-enabled.
In-channel Compel Control
Compel is the name of the system used for control of most WEGENER products. It is used
in a “star” (point-to-many-point) control structure, where Compel will be controlling many
“edge” devices (called “receivers”) that deliver media content at remote locations. It is a one-
way control system that essentially depends on a command redundancy in a moderate-reliability
channel, with refreshes to maintain synchronism between its database and the actual state of the
receivers. WEGENER’s Return Path product, at this writing, is not yet used to fully synchronize
the remote receivers to the database, except in some special cases (to be discussed). In this
section, Compel commands are presumed to be borne in-channel, that is, in a designated “ghost
PID” in the MPEG Transport stream, injected by WEGENER UMX5010s. This in-channel
control system presumes that receivers will execute their received commands immediately, and
that they will be executed in order of arrival, with the last command always taking precedence, if
the receiver setting is to be changed.
This Manual cannot discuss Compel to exhaustion. The user is referred to their Compel
Manual and associated Informative Bulletins. However, the basic types of Compel commands,
their structure and basic applied rules, and their addressing rules may be briefly reviewed herein.
Command Types:
• Grouping commands: Commands that assign a receiver to a logical group, which,
in turn, may be used as an address for other commands, including other grouping
commands. A more advanced grouping mechanism, the Group Page, may also be
employed. While a receiver may be a member of up to 10,000 groups, it may have
only one Group Page membership (generally a value between 1 and 255).
• Receiver state commands: Commands that change a receiver setting and whose
new value is retained in Compel’s internal database.
• Meta commands that are a special set of the above state commands: These affect
the unit’s ability to process control from Compel or other sources. An examples is
the Compel LOCK command, which prevents the receivers from executing any other
command except the companion UNLOCK command. Another example is the
LOCAL CONTROL enable/disable commands. These serve to block the local user
from innocently changing critical receiver settings that would directly affect revenue
(though they cannot block malicious actions).
• Receiver action commands: Commands that stimulate a receiver to execute a
particular function, usually limited in time. It is assumed that the long-term state of