Cygnus 1 Operation Manual page 15

Valid-Reading packet arrangement
7 byte sequence :
1. SOH [hex 01]
2. Status-byte
3. Data-byte 0
4. Data-byte 1
5. Data-byte 2
6. Data-byte 3
7. ETB [hex 17]
No-Reading packet arrangement
3 byte sequence :
1. SOH (hex 01)
2. Status Byte
3. ETB (hex17)
Status-byte structure
decodes into bit-fields :
bit 7 - ms Cygnus Gauge type
bit 6 Reading Resolution
bit 5 Measurement Units
bit 4 Reading Range
bits 3, 2 Echo Count
bit 1 Calibration
bit 0 - ls No-Reading flag
Data-bytes arrangement
The four data bytes are ASCII-encoded, decimal thickness value
Data byte 0 is most-significant
Leading-zeroes are replaced by ascii Space [hex 20]
Decimal points are implied from the Status-byte – Units, Resolution and Range bits :
Reading-type
Imperial, Lo-Resolution
Metric, Lo-Resolution
Imperial, Hi-Resolution
Metric, Hi-Resolution
HI = Mark2+
[LO = Mark1 – not used]
HI = Hi-Resolution
LO=Metric
HI = Imperial
HI = Hi-Range
0 to 3 Echoes found
HI = Remote
LO = Local
HI = No-Reading
LO = Valid-Reading
Hi-Range Lo-Range
x x . x x x . x x x
x x x . x x x x . x
x x . x x x . x x x
x x x . x x x . x x
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