One of the advantages of connecting directly to a host computer is that a separate IQ interface
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:
Figure 3.2 RS232 Cable Wiring
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
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
19.2K 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
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
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