Important: Do not use twisted pair wire for RS232; because it increases crosstalk. Instead, use an un-; twisted cable or ribbon cable.- Page 11

Page 11

IQ–AMB-5 / IQ–SMX-6

 Reference Manual

AMB-5 / SMX-6

  IQ Mixer/Multiplexer

One of the advantages of connecting directly to a host
computer is that a separate IQ interface (IQ

–INT-II) is

not required. If you plan to configure the unit while it is
connected to the Crown Bus, skip ahead to Section
3.2.

RS232 is commonly used with IBM PCs and com-
patibles, and is the communication standard sup-
ported by the mixer/multiplexer when used as an
interface. Because it uses unbalanced signal wiring, it
cannot be used for distances over 50 feet (15.2 m).

The following illustration shows how to wire the serial
cable:

Important: Do not use twisted pair wire for RS232
because it increases crosstalk. Instead, use an un-
twisted cable or ribbon cable.

Setting the communication parameters for RS232 se-
rial communication is accomplished using the six-seg-
ment baud rate and parity DIP switch shown in Figure
3.3. The first four switches select the baud rate and the
last two set the parity. Use the fastest baud rate pos-
sible. The highest baud rate supported by the unit is
19.2 K baud. Parity checking is not supported and
should be OFF. The odd/even parity bit setting doesn't
matter when parity is switched OFF. The unit has been
factory set to 1 stop bit and 8 data bits.

The communication parameters of the host computer
are set by the IQ software. Please refer to the IQ
software documentation for information about setting
up communication parameters.

Here are some important guidelines when configuring
serial communication:

• Use the same communication parameters at

each end. The unit and the computer must be set
for the same baud rate and parity checking.

• Use the highest baud rate possible. IQ mixer/

multiplexers can be set as high as 19.2 K baud.

• If the host computer fails to communicate with the

unit and the communication standard and pa-
rameters are set correctly, try reducing the baud
rate of both the unit and the computer.

• If communication problems persist, check the se-

rial cable for improper wiring or possible shorted
or broken wires.

• For further assistance contact the Crown Techni-

cal Support Group (see Section 8 for contact in-
formation.)

3.2 Connecting to the Crown Bus (Step 2)

The Crown Bus is a serial communication loop de-
signed to transmit IQ commands and data. As a com-
munication standard, it is independent of the wiring
system used. This flexibility is a great strength, en-
abling a Crown Bus loop to be wired with either fiber
optic cabling or with inexpensive twisted-pair wire,
whichever the installation requires. A single 

IQ System

can have more than one Crown Bus loop. To function
properly, a Crown Bus loop must be unbroken.

3.2.1 Set the IQ Address Switch

By giving each IQ component a unique address, it can
be individually controlled and monitored. Whenever
the IQ System wants to send a command to just one IQ
component, it first sends its address and then the
command down the Crown Bus.

The IQ Address switch has eight segments because it
actually contains eight tiny switches inside. The switch
is shown in Figure 3.3.

Each of the eight segments in the IQ Address switch
have a value which doubles as the number increases.
For example segment 1 has a value of 1; segment 2
has a value of 2; segment 3 has a value of 4; segment
4 has a value of 8 and so on.

The address is determined by adding the values of all
“ON” segments. In Figure 3.3, segments 2, 5, 6, and 7
are on. Simply add the values to find the address:
2+16+32+64=114.

A convenient series of IQ address tables are included
in Section 7. The tables show the switch settings for all
250 addresses.

No two IQ components of the same type which are
connected to the same Crown Bus can have the same
address. Suppose, for example, an IQ System has two

Figure 3.2 RS232 Cable Wiring