Product Alert #49
Model 6004, 6526, 8007, 7001 Loggers
Logger Losing Time (Slow Clock)
27 October 1999
Problem
A timing issue on the above loggers may cause them to lose time. If a scan is scheduled to start within 10 microseconds of the logger switching off, the scan may be missed.
Under typical conditions this will never be a problem as all loggers are switched off hundreds of milliseconds before the next scan is scheduled to start (100ms may sound like a short time, but it is 10,000 times longer than 10µs).
This problem has so far only been apparent in a system where the logger was configured as an SDI-12 sensor, and it was being continuously interrogated. Not even continuous RS-232 interrogation (eg. the software Test Display) would reveal this problem.
Correction
To correct the above problem, upgrade your logger firmware. If you have Version 3 software,
download new firmware and update your logger, otherwise contact your
nearest Unidata office.
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