Michell Instruments QMA401, Руководство пользователя

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QMA401 User’s Manual
76 97450 Issue 2, March 2018
APPENDIX C
0000 = Moisture – PPMv (def)
0001 = Moisture - PPMw
0010 = Moisture – MGM3
0011 = Moisture – PA
0100 = Moisture - LBMMSCF
0101 = Dew point
0110 = Oven temperature
0111 = Flow rate
1000 = Cell Pressure
1001 = Ext Line Pressure
0000 = Moisture – PPMv
0001= Moisture - PPMw
0010 = Moisture – MGM3
0011 = Moisture – PA
0100 = Moisture - LBMMSCF
0101 = Dew point (def)
0110 = Oven temperature
0111 = Flow rate
1000 = Cell Pressure
1001 = Ext Line Pressure
Output Type – (T1 to T2)
0 = 4–20 mA
1 = 1–5V
(Where T1 is CH1 and T2 is CH2)
Register Configuration H — Time (hours/minutes)
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
HH HH HH HH HH HH HH HH MM MM MM MM MM MM MM MM
Hours Number (HH) Minutes Number (MM)
00 to 23 00 to 59
Register Configuration I — 32 bit Precision Floating Point Representation
IEEE-754 single precision floating point format. This format is 'Big Ended' which means that the
high byte is at a lower address in memory than the Lo byte, and is represented as such in the
register memory map. The IEEE-754 format is shown below.
Bit 31 Bits 30 to 23 Bits 22 to 0
Sign bit
0 = +
1 = -
Exponent Field
Has a +127 bias value
mantissa
Decimal representation of binary.
Where 1.0 <= value < 2.0
Examples of floating point to HEX are shown below:
1. +10.3
sign bit = 0
Exponent = 3, therefore exponent field = 127 + 3 = 130 , and bits 30 to 23 = 1000 0010
The mantissa = 1.2875 which in binary representation = 1010 0100 1100 1100 1100 1101
Adjusting the mantissa for the exponent moves the decimal point to the right if positive and to the
left if negative.
As the exponent is = 3 then the mantissa becomes = 1010 0100 1100 1100 1100 1101, therefore:
1010 = (1x23) + (0x22) + (1x21) + (0x20) = 10 and
0100 1100 1100 1100 1101 = (0x2-1) +(1x2-2) + -- + (1x2-20) = 0.3
Therefore the word value = 0100 0001 0010 0100 1100 1100 1100 1101
= 4124CCCD