Introduction
13
SERIAL DATA FORMAT
CygLink program is provided to automatically decode the measurement data sent from the
Gauge, and to provide a calibrated display of the results
For users who want to display and log the data using their own software : this describes the
arrangement of the data sent from the Gauge
Data Communication Format
¾ Data Output Standard
Ö Differential RS-422 line drivers [TX+, TX-]
Ö Unidirectional - Gauge is transmit only
¾ Data-byte Format
Ö 8 Data bits, 1 Start bit, 1 Stop bit, No Parity; 2400 baud
¾ Data-Packet Arrangement
Ö 4 packets per second
Ö Valid-Reading packet-length : 7 bytes
Ö No-Reading packet-length : 3 bytes
Interpreting the Reading sent from the Gauge
¾ Scaling
Ö The Gauge takes measurements using an accurate fixed-rate crystal oscillator
Ö Readings are scaled for an equivalent Velocity of Sound of 6400 m/s
Ö Displayed readings have to be scaled by multiplying by the Velocity of Sound (in
m/s) for the Material-under-Test, and then dividing by 6400
Ö Decimal Point position is implied from the combination of Range, Resolution, and
Units bits in the Status byte of each Reading [see table below]
¾ Range
Ö The Gauge returns all Readings in a 4-byte decimal string
Ö Readings which require 5-bytes [eg 100.00+mm, or 10.000+inch] are autoranged to
the 4 most significant bytes
Ö Range bit for every Reading must be read from the Status-byte
¾ Resolution
Ö The Gauge has a default Hi-Resolution setting : 0.05 mm, or 0.002 inch
Ö Lo-Resolution setting is not normally used : 0.1 mm, or 0.005 inch
Ö Resolution bit must be read from the Status-byte
¾ Units
Ö The Gauge has a default Metric Units-setting
Ö Units bit must be read from the Status-byte
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