Manual-24
Notes
1. When the value $FB occurs anywhere except in an ADDR header, it is repeated.
2. The data size is the number of bytes, prior to the $FB repetition, between the command code and the checksum inclusively.
3. The checksum applies to the “data size” bytes through the byte immediately before the checksum, inclusive. Repeated $FB’s
are counted only once. The sum is the two’s complement negative of the LS Byte of the arithmetic sum. For example, if the
sum is $1234, the checksum is $CC.
4. The parameter bytes are indexed using a 2-byte number (MSB first) starting with 0. The number of parameter bytes also uses a
2-byte number with the same format. When sending parameters, the number sent is determined by the data size.
5. The working/stored flag is set if the working memory doesn’t match the stored memory from which it originated.
6. The working/dirty flag is set when the unit is powered up, or when a memory is recalled. It is cleared when the working
parameters are sent or received.
RW 232 Communications Interface
RW 232 is loosely based on PA-422. One key hardware difference is that RW 232 does not utilize hardware handshaking via
DTR/DSR. The beginning of a message always takes the form:
$FB xx FB xx (where xx = ADDR)
Note: When $FB appears in the body of the message, it is always repeated.
Input port:
9-pin female input port (DB-9F) on device
Output port:
9-pin male output port (DB-9M) on device (for serial linking to the input port on the next device. Upto 16 devices
can be linked in this manner.)
Device address means:
4-position DIP switch on device (valid device addresses are 1 through 15)
Baud Rate:
19.2 kilobaud
Character frame bits:
1 start bit, 8 data bits, 1 parity bit (even), and 1 stop bit
Cabling:
Use standard RS-232 serial printer or modem cables.
Warning:
NULL modem cables will not work!
Host or computer interface:
Standard PC serial COM port (DB-9M, or DB-25M with adapter)
Note: Only three lines, Tx, Rx, and Ground, are used.
References
Rodgers, Robert L., “PA-422 Communications Interface and Device Control Language”, Journal of the Audio Engineering
Society, Vol. 38, Number 9, 1990 September, pp. 619-639.
Audio Engineering Society, Inc., “AES Recommended practice for sound-reinforcement systems-Communications interface
(PA-422)”, Journal of the Audio Engineering Society, Vol. 39, Number 9, 1991 September, pp. 664-679.
Standards documents: AES15-1991 (Audio Engineering Society) ANSI S4.49-1991 (American National Standards Institute)
