Troubleshooting — 7
Notes
Rev 3-97
* School
nication. Because data flows one direction around the loop the component will
assume that it can still send a message out to downstream components and
back to the interface. The component begins to continuously dump its
identification. If there is continuity back to the interface data input the interface
will carry the data stream of that component’s identification through the RS232
line and back to the computer. When the Break Detect feature of the software
is enabled it will listen for such a stream and report it to the operator. Because
the information reported includes the loop address and type of component you
can tell that the break in the Crown Bus is in the line coming into the specified
component.
Break Detect works with breaks that result in loss of current continuity in the
Crown Bus cables. Remember that a break may be an open cable (positive or
negative side) or a polarity reversal of the cable. Note that a hardware failure
of the input isolator device or output current driver also constitutes a break.
Break Detect will not find a capacitance problem, nor will it find an RFI problem.
More specialized utility programs may be required to run specialized tests for
problems like that.
Break Detect is a feature you want on in most cases. It reports a break at the
time it occurs.
Search (DOS Software Only)
Another feature found on the F10 control panel screen that is used to diagnose
system communication problems is simply called Search. Search is a manual
break detection process that you can run at any time. It checks a specified loop
for continuity in the same manner as Break Detect. It is a feature you would use
if you were not able to establish loop communication initially, you missed the
alert on the screen, or you want to verify the break. To use Search you need to
select the loop to search then toggle the Search feature on. It goes off
automatically when it is done performing its check.
When you perform a Search you usually get one of three messages. If the loop
is intact and there are no problems it gives you a message that says the loop
is okay. If there is a break at the input of an IQ component with an address the
software will tell you the location of the break. If the break occurs at the input
to the interface or the input to a non-addressable item, such as a Repeater or
fiber optic receiver, a message will appear that says it cannot locate the break,
the break may be before the first component.
All Amps
A special set of features exist in the software that can prove particularly useful
in large amplifier systems. As much as Crown might like to sell systems with
large numbers of automatic mixers, relay cards, or other devices, most IQ
Systems with a relatively large number of components are primarily amplifier
systems. For this reason special All Amps features are in the software to turn
all amplifiers in the entire system on or off, mute or unmute, or all Data LED on
or off. The All Amps features actuate all amplifiers on any loop regardless of
address and regardless of whether they are in the dataframe inventory.
As a diagnostic tool the All Amps Data LED controls may be very helpful in
amplifier systems to locate a break if other software features such as Break
Detect or Search fail to locate the communication problem. When Data LED is
turned on for all amplifiers using the All Amps control, all amplifiers that receive
the message turn on their Data LED indicator. After forcing on Data LED
