Biamp EQ28X RS-232 User Manual

RS-232 Control

of the

Advantage EQ281/8, EQ282/8

and Advantage SMS200

________________________________________________________________________________________

Biamp Systems, 14130 N.W. Science Park, Portland, Oregon 97229 U.S.A. [phone]

an affiliate of Rauland-Borg Corp.

Introduction

This document contains technical information relating to computer control of the Biamp
Advantage EQ282/8 dual channel digitally controlled graphic equalizer. The command
set described in this manual also applies to the Advantage EQ281/8 (which is a single
channel version of the EQ282/8) and the Advantage SMS200 Sound Masking System
(which is an EQ281/8 with internal pink noise generator).

This information is intended for advanced users - in particular for those who wish to
develop their own computer programs to control these equalizers. It is assumed that the
reader is an experienced programmer and has some familiarity with standard programming
practices, binary and hexadecimal numbers, the ASCII character set, asynchronous serial
data communications, and RS-232 interfaces.

Hexadecimal, ASCII-Hex, and "Pseudo-Hex" Numbers

Throughout this document, hexadecimal numbers shall be represented by preceding the
number with "0x". For example: the hexadecimal equivalent of the decimal number 255 is
0xFF.

Individual ASCII characters, except control characters, will be enclosed in single quotes.
For example: the ASCII character 'A' has the hexadecimal value 0x41. The ASCII
"carriage return" control character shall be represented as ↵. An ASCII code chart is
included with this document for your convenience.

When an 8-bit binary data value is being transmitted over a serial data communications
link, it is a common practice to transmit the byte as two "ASCII-hex" characters - one
character represents the most significant nibble of the data value and the other character
represents the least significant nibble (a nibble is 4-bits; half of a byte). Each ASCII-hex
character is in the range of '0' thru '9' or 'A' thru 'F' (from the ASCII code chart, 0x30 thru
0x39 or 0x41 thru 0x46). For example, the hexadecimal equivalent of the decimal number
61 is 0x3D. To transmit this in an ASCII-hex format, first transmit the ASCII character '3'
(whose hex value is 0x33), followed by the ASCII character 'D' (whose hex value is 0x44).
This is the standard way to transmit an ASCII-hex value. In some cases, the lower case
characters 'a' thru 'f' (0x61 thru 0x66) are accepted in addition to the upper case letters 'A'
thru 'F'.

The Advantage EQ282/8 does not utilize standard ASCII-hex format. The EQ282/8
computer commands implement what I call "pseudo-hex" notation (also sometimes
referred to as a "poor man's" ASCII-hex notation). Instead of representing the
hexadecimal value using the ASCII characters '0' thru '9' and 'A', 'B', 'C', 'D', 'E', and 'F',
the pseudo-hex format uses the ASCII characters '0' thru '9' and the characters ':', ';', '<',
'=', '>', and '?'. As you can see by studying the ASCII code chart, a binary nibble may be
converted to its equivalent pseudo-hex character by simply adding 0x30.

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Computer Control of the Advantage EQ282/8, EQ281/8, SMS200 page 1

A binary/decimal/hexadecimal/pseudo-hex conversion chart is included at the end of this
manual for your convenience.

Data Communications Parameters

The Advantage EQ282/8 has a rear-panel dip-switch which allows you to set its baud rate
to either 2400, 9600, or 19200 bits per second. The factory default setting is 9600. The
EQ282/8 communicates with 8 data bits, no parity, and 1 stop bit. The EQ282/8 utilizes a
subset of the standard 7-bit ASCII character set.

The Advantage EQ282/8 utilizes interrupt-driven communications firmware with a 32­character receive buffer. When the EQ282/8 receives a command, it may become “busy”
for as long as 250 milliseconds while it is executing the command. During this time, the
EQ282/8 can successfully receive up to 32 additional characters. If more than 32
characters are sent to the EQ282/8 while it is busy executing a command, its input buffer
will be overrun and some characters will be “lost”.

To avoid overrunning the Advantage EQ282/8’s input buffer, it is recommended that
some form of flow control be implemented. Neither hardware (DTR or RTS) nor
XON/XOFF (also known as DC1/DC3 or control-S/control-Q) handshaking is supported
by the EQ282/8. However, each character which the EQ282/8 receives through its serial
port will be "echoed" back to the computer. A simple form of flow control may be
implemented by simply waiting for each character's echo from the EQ282/8 before
transmitting the next character, since the EQ282/8 doesn't retrieve and echo an incoming
character until it has finished processing the previous character.

Computer Control

The Advantage EQ282/8 has an RS-232-compatible serial port which allows it to be
controlled by a computer or by a system controller such as those provided by AMX or
Crestron. The EQ282/8 offers the following two methods of computer control:

• Control Button Emulation. This method of computer control allows the computer to

emulate Biamp's standard infrared remote control transmitter or wall-mount remote
control panel. Using this method, the computer outputs ASCII characters which are
equivalent to the characters which would be generated by a Biamp remote control.
These ASCII characters are transmitted from the computer to the EQ282/8’s serial
port. In order to use Control Button Emulation with an EQ282/8, you must first use
Biamp’s Windows 95-based PC Control Software Package to establish “button”
definitions for the device. Control Button Emulation is simple to perform, however, it
only provides "one-way" control of the EQ282/8 - it allows the computer to send
simple commands to the EQ282/8, but it does not provide any mechanism for
requesting status information from the EQ282/8.

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21-Jul-97

• Advanced Computer Control. This method of computer control provides advanced

commands which allow "two-way" control of the Advantage EQ282/8. Using
Advanced Computer Control commands, the computer may request status information
from the device as well as send commands to the device. The computer communicates
with the Advantage EQ282/8 using the Advantage EQ282/8’s serial port.

Control Button Emulation

Control Button Emulation is the simplest form of computer control of the Advantage
EQ282/8. This method of operation allows the computer to emulate the operation of a
standard Biamp remote control transmitter. This may seem a little strange since, unlike
most of Biamp’s other computer-controlled products, the EQ282/8 does not actually have
a remote control port. However, the EQ282/8 still implements control button emulation
for situations where the EQ282/8 is linked (via serial port) to other Biamp products which
do have remote control capability.

For each button on a standard Biamp remote control, there is a corresponding ASCII
character. In order to emulate a remote control button, the computer simply transmits the
corresponding ASCII character to the Advantage EQ282/8’s serial port. Each character
received by the EQ282/8 will be echoed back to the computer.

The following table summarizes the ASCII character codes for Control Button Emulation
corresponding to each of the 40 remote control buttons supported by the Advantage
EQ282/8. These button codes are also summarized on the ASCII code chart provided at
the end of this manual. The remote control buttons on the standard Biamp transmitter are
numbered from left to right going from bottom to top with the lower left-hand button
being button number 1. When the EQ282/8 is shipped from the factory, all remote control
button definitions are set to “nop” (no operation) - in order for Control Button Emulation
to be useful, you must first use Biamp’s PC software to create some button definitions
which actually do something (recall preset curves, for example).

Control Button Emulation ASCII Codes

button 1 'B' (0x42)
button 2 'C' (0x43)
button 3 'D' (0x44)
button 4 'E' (0x45)
button 5 'F' (0x46)
button 6 'G' (0x47)
button 7 'H' (0x48)
button 8 'I' (0x49)
button 9 'J' (0x4A)
button 10 'K' (0x4B)
button 11 'L' (0x4C)
button 12 'M' (0x4D)
button 13 'N' (0x4E)
button 14 'O' (0x4F)

button 15 'P' (0x50)
button 16 'Q' (0x51)
button 17 'R' (0x52)
button 18 'S' (0x53)
button 19 'T' (0x54)
button 20 'U' (0x55)
button 21 'V' (0x56)
button 22 'W' (0x57)
button 23 'X' (0x58)
button 24 'Y' (0x59)
button 25 'Z' (0x5A)
button 26 '[' (0x5B)
button 27 '\' (0x5C)
button 28 ']' (0x5D)

button 29 '^' (0x5E)
button 30 '_' (0x5F)
button 31 '`' (0x60)
button 32 'b' (0x62)
button 33 'c' (0x63)
button 34 'd' (0x64)
button 35 'e' (0x65)
button 36 'f' (0x66)
button 37 'g' (0x67)
button 38 'h' (0x68)
button 39 'i' (0x69)
button 40 'j' (0x6A)

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