4 — Troubleshooting
Notes
Rev 3-97
@ Crown
very important to verify that the system is, in fact, working after you perform a
repair.
Example: Plug the cable back into the PIP then run a Roll Call to verify that all
system components are on line then verify that the amplifiers respond to
commands sent from the computer.
COMMON IQ SYSTEM PROBLEMS
Most IQ System problems occur at the time of installation. Most of those are
related to hardware or software communication setup. Other than hardware or
software settings, loop capacitance is a significant factor. In many cases wire
selection is becomes a critical factor. In longer loops where capacitance is
questionable it may be necessary to add an IQ-RPT Repeater to the loop.
Hardware Setup
Switches are a necessary evil in the setup of any IQ System. Component
addresses must be a valid value with no duplicates of same type of component
on the same Crown Bus loop. Baud, parity, and any other hardware switch
settings on the component serving as system interface must be properly
configured. Parity should, except in very unusual circumstances, be off. The
computer, software, and RS232/422 cable must be capable of supporting the
baud selected at the interface. AC power must be available and the interface
must be on. RS232/422 cable must be connected at both ends to the proper
computer serial port as well as the proper IQ System component. You must
have a 16550 UART for the computer com port. The computer itself must meet
the minimum requirements for the type of software being used.
IQ components are not likely to fail, but it is not impossible. Lightening is a
respecter of no one. The most common type of hardware failure is opto-isolator
damage due to high voltage spikes from lightning or other power sources. The
only other major source of hardware failure is failure to follow proper static
handling procedures of components with exposed static sensitive electronics
such as PIP module and card cage components.
Software Setup
Most software parameters that affect whether or not you can communicate
properly with the system in DOS software are found on the F10 control panel
screen. In IQ For Windows both the program communication settings and the
Windows Control Panel effect communication. At a minimum those settings
include com port enable, com port number, IRQ number, Base Address, and
baud.
Crown Bus Loop
The Crown Bus is a communication standard based on the transmission of
proprietary IQ command protocol on a serial data loop. Although other media
may be used to transmit the protocol, IQ hardware uses 20 ma current as the
media to go into and out of components. Digital signals are, by their nature,
simply pulses of DC. This in turns means that data signals are polarity sensitive.
One of the most common mistakes made when wiring Crown Bus connections
is to reverse the polarity of a Crown Bus cable. A broken or unplugged cable
or polarity reversal anywhere in the loop consitutes a break in the loop. When
the IQ-INT II unit is used as the interface a common problem is to have the input
and output lines for one loop connected to the interface output of one loop and
the input of another loop at the interface.
