AvaLAN Wireless AW900R4-EVAL - Manual (Page 8)

User’s Manual
PAGE 8 Technical support (650) 384-0000 www.avalanwireless.com
AW900R4-EVAL
Serial Port Settings These settings must match those of the RS-485 bus connected to the module.
Baud Rate Drop down menu providing six choices from 9600 Baud to 115,200 Baud (se-
rial data rate).
Data Bits Selectable 7 or 8 data bits (8 is the most common choice)
Parity Selectable among “none”, “even”, “odd”, “mark” or “space” (“none” is the
most common choice)
Stop Bits Select 1 or 2 stop bits (2 is the most common choice)
Tuning Parameters These affect the behavior of the RF packet transmissions relative to the
incoming serial data. We suggest leaving these at the default values unless
the nature of the serial data or the requirements of the protocol being used
demand otherwise.
Next Byte Delay The amount of time the bus must be idle after the Minimum Packet Size has
expired before the radio sends everything in it’s serial buffer. Values of 00 to
10 may be chosen, with a default of 00. Each unit of time is the reciprocal of
the Baud Rate (e.g. 104 µs at 9600 Baud).
Minimum Packet Size Expected packet size bytes. Values of 01 to 99 may be chosen, with a default
of 01. Packets smaller than this will wait to see if additional packets arrive
during this time window. If additional packets arrive, they will be combined
into a single transmission.
Maximum Packet Size Maximum number of bytes per transmission. Values from one more than
the Minimum Packet Size to 768 may be chosen with a default of 024 bytes.
Packets larger than this size will be sent over the RF as fragments and reas-
sembled at the receiver radio.
7. Here is additional information about the tuning parameters. The data protocol
you are using may require certain groupings of the bytes or particular timing of the
information:
• If you want minimum latency so that data is received as soon as possible af-
ter it is sent, select a Next Byte Delay of 00 and a Minimum Packet Size of 01.
• If you are sending large blocks of data, a Minimum Packet Size of 01 can
cause the AW900R4’s buffer to overflow and bytes will be lost. The value can
be increased to a maximum that depends on the Baud Rate, corresponding to
about 5.3 milliseconds:
Baud Rate largest Minimum Packet Size
9600 5
19200 10
38400 20
57600 30
76800 40
115200 60