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"DER query" frame format –the data display system to the detecting unit
D7
D6
D5
D4
0
1
0
1
1
0
1
0
0
0
0
0
* - 0Fh address – broadcast address. All detecting units respond to the query with such address.
"Current DER" frame format –the detecting unit to the data display system
D7
D6
D5
D4
0
1
0
1
1
0
1
0
0
0
0
1
DER0 (low byte)
DER1
DER2
DER3 (high byte)
Byte
D7
0
0
0
control
* - measurement result is accepted as not reliable if the statistical error of measurement exceeds the maximum permissible
error of the measurement
D3
D2
D1
D0
0
1
0
1
Byte 55h – start-of-frame character
Byte AAh
1
0
1
0
А3
А2
А1
А0
D3
D2
D1
D0
0
1
0
1
Byte 55h - start-of-frame character
Byte AAh
1
0
1
0
D7...D4 - "Current DER" frame code
А3
А2
А1
А0
D3...D0 - detecting unit address
DER,
fixed point number,
Least significant bit (LSB) = 0.01 µSv/h
Statistical error of measurement
D0,D1 – self-testing results of the
D0=1 – failure of the high sensitivity
D1=1 – failure of the low sensitivity
0
D2
D1
D0
Reliable measurement result character
D2=0 – result is reliable
D2=1 – result is not reliable *
D7=0 – LSB DER = 0,01 µSv/h
D7=1 – LSB DER = 0,1 µSv/h
arithmetical checksum with a carry
D7...D4 – "DER query" frame code
D3...D0 – detecting unit address *
detecting unit
detector
detector
27
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