Section 2:
Configuration
Revision 1.0a
37
© 2006 Intuicom, Inc.
If no timeout, set this value to 0. This is appropriate for applications with measurement
data such as GPS monitoring or seismic data collection.
Data Accumulation Delay
The Data Accumulation Delay parameter configures the amount of time to allow data to
accumulate in the buffers before forming a Navigator packet and transmitting it to the
Master. If the data stream is periodic, calculate the amount of time necessary to transmit
the packet of data from the attached device to the Navigator IIm at the port’s baud rate
(for example, if Port B were configured to 19200 baud, a data packet of 500 bytes would
take approximately 210ms). The default value of 100ms works well for most
applications.
Max Random Transmit Delay
Max Random Transmit Delay controls the amount of time to wait after forming a
Navigator packet before attempting to send it wirelessly. The parameter randomizes each
unit’s access attempts to the master and breaks up highly synchronized data generators
such as GPS. The default value is 300ms meaning that every time the unit has data to
transmit it will wait between 0 and 300ms before attempting to send the data.
2.5.4 Data Packet Configuration
Data Packet Configuration allows the user detailed control over how the unit forms a
Navigator packet. Using knowledge of the data generated by attached devices, the user
can configure the maximum packet size, and the maximum amount of that size occupied
by data from each Port, including the embedded GPS.
First configure the maximum size of a Navigator Data packet. The default is 512 bytes,
while the maximum allowed size for a Navigator packet is 2048 bytes. Larger packet
sizes are useful if the attached device generates a larger amount of data in a given cycle.
Larger packets are mode efficient by reducing overhead. Smaller packets are useful
when an attached device has smaller amounts of data, but may be more time sensitive.
Each Port’s configuration has two parameters, a priority and a minimum number of bytes
to reserve. The minimum number of bytes reserves this number of bytes in a given
packet if that port has at least that number of bytes available. This allows connected
devices with a comparatively small amount of data to send to be able to ensure that their
data can be sent with every Navigator packet if they have data to transmit.
The priority controls how any extra available space in a packet is filled. If after first
examining the buffers, and attempting to fill each ports minimum reserved number of
bytes, it is determined that there is more data in the buffers ready to be sent – the priority