Starret DataSure, Руководство оператора

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DataSure™ Operators Manual 30 PT 6*****
show the user that data transmission has failed, a few good things can result. The operator can
immediately see that there is a problem with the network and correct it. Conversely, without any
system status indication, the operator can unknowingly corrupt his own data collection. The
operator can also stop pressing the data send button, which may send many duplicates of the
data. Unfortunately, repeated pressing of a button is a typical or perhaps a natural response when
an electronic device does not work as expected. By repeatedly pressing the data send button to
“remedy” the problem, the data set will be corrupted and therefore corrupting the data sets
statistical significance. Additionally, without system feedback, the operator may continue to
think everything is ok for sending data, continuing the data collection process but lose an entire
shift worth of data collection. This is an undesirable situation indeed.
With a feedback method of system status oriented to the user, data can have more integrity.
However, when the user ignores or misses the feedback, data can still be corrupted. As an
additional safeguard to lost data, the endpoint radio can incorporate a means to store data
recorded when the main systems is down. Often operators will take measurements quickly, yet
accurately in a production environment. After taking e.g. 15 successive measurements with rapid
button pushes, and the system crashes on the 10
th
measurement, then the remaining 5
measurements would be lost. Modern wireless data collection system designs incorporate a
storage feature that collects any data “taken” at the endpoint and holds it until the system
becomes available again. All the while data is being stored on the endpoint, the endpoint radio
alerts the user with the feedback system described above and waits for the system to come back
online. Once the system is back on line, the endpoint will dump its data to the gateway/PC host
system. No data is lost, even though the main system has failed.
During the OTA (over the air) transmission of data, a wide variety of interferences can occur and
modern systems have mechanisms to identify corrupted data and mark the data as such. By using
CRC (cyclic redundancy check(ing)) and parity error detection methods, modern systems can tag
or discard the corrupted data, unfortunately, most systems today just do that. There is no chance
of recovering the intended measurement. Advanced systems, such as The LS Starrett’s wireless
data collection system, has a system feature communicates between endpoint and gateway that
seeks to insure that uncorrupted data arrives at the gateway. If the system tags the data sent with
a CRC or parity error, the gateway informs the endpoint to resend the data again from the
endpoints temporary memory. Data is then sent again, up to 10 times, to insure good data
ultimately gets to the data set. If data is received as good, then the gateway informs the endpoint
to discard its temporary memory of that data, so that it doesn’t get sent again. The temporary
memory is only held until the gateway validates a successful receipt of the data.
These methods are just some of the ways the LS Starrett Wireless Data Collection System
insures very high data integrity. Data collected in the field show some remarkable performance
figures. Typical successful measurement transmissions up to zero failures in 3.5 million
measurements have been recorded.
3.4 Monitoring Device Statistics
Administrators encountering problems with data exchanges over the wireless network
have the opportunity to monitor the performance of EndNodes through the Device Statistics