Lord MicroStrain Sensing SG-Link-200, User Manual

Page: 24 / 52

SG-Link®-200
User Manual
24
5.2 Network Options
There are two network protocols available for the SG-Link-200, LXRS and LXRS+. These feature
node-to-node synchronization of 50us, and unmatched lossless wireless sensor network data
throughput. MicroStrain Sensing created these specifically for applications such as flight test and
heavy machinery monitoring, where large amounts of raw data are generated, and node
synchronization is important. The principal difference between the two protocols is that LXRS+
sacrifices communications range, in favor of a 4x greater network bandwidth.
l
Synchronized - All nodes in the network will periodically synchronize their time clocks to a
beacon that is broadcast each second by the WSDA gateway. Each beacon contains a
UTC timestamp, allowing nodes to align their collected data within an accuracy of +/- 50 us.
Each node will also buffer data and transmit this data in time-slots allocated prior to
sampling. Using time-slots assures the transmissions will not “collide”, or corrupt each
other. It also provides a means for efficiently scaling the size of the network to allow as much
data throughput as possible.
l
TDMA Networking- The user can achieve near lossless data collection in most
environments using data buffering, radio acknowledgments, and retransmissions. Each
node buffers collected data and timestamps to an internal 2 Mbit FIFO buffer. For each
transmission, data is pulled from this buffer. The node will retransmit data until this
acknowledgment is received. Inherent overhead in the transmission scheduling protocol
assures the node time to recover from periods of poor radio communication. This feature
allows lossless performance in environments where the node achieves as low as 50%
packet error rate. It also allows for operation in situations where the gateway and node
move in and out of range of each other.
More detail on network topology and data handling will be found in a technical brief,
“LXRS and LXRS+ Wireless Sensor Protocol”, which will be found under documentation
for each wireless product on the MicroStrain website.