Rosemount 2700, Инструкция по эксплуатации, Страница: 43 / 94

A-9
MODEL 2700 APPENDIX A
SERIAL COMMUNICATIONS PROTOCOL
B3 B2 B1 B0
‘C’ ‘C’ ‘4’ ‘1’
E00 M22 M21 M20 M19 M18 M17 M16 S00 E07 E06 E05 E04 E03 E02 E01
1 1 0 0 1 1 0 0 0 1 0 0 0 0 0
From IEEE Std 754-1985:
measurement value = (-1)^sign * 2^(exponent-127) * 1.mantissa
sign = S00
exponent = E07 E06 E05 E04 E03 E02 E01 E00
mantissa
= (M22 M21 M20 M19 M18 M17 M16 M15 M14 M13 M12 M11 M10 M09
M08 M07 M06 M05 M04 M03 M02 M01 M00) / 2^23
sign = 0
exponent = 1 0 0 0 0 0 1 1
= 31
mantissa = (1 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0) / 2^23
= (4C0000 hex) / 2^23
= (4980736) / 8388608
= 0.59375
measurement value = (-1)^0 * 2^(131-127) * 1.59375
= 25.5
1.3.7 Send Scale Factors 77H/119
Scale factors convert measurement values in Solu Cube RAM to the value on the Instrument display. To calculate the
displayed measurement, multiply the measurement from Read RAM or transmitted via the Send Measurement command
by the Scale Factor for the Display Units. Read RAM to find the Display Units.
For a complete list of Units and Scale Factors, see “Serial Communication Tables”.
To 2700 ADDR CMD
From 2700 ADDR CMD MAX1 MAX0 S1 S0
ADDR: Instrument Address
CMD: 77H
MAX1: MSB of number of scale factors sent
MAX0: LSB of number of scale factors sent
S1: MSB of scale factor
S0: LSB of scale factor
S1 and S0 repeat for the number of scale factors sent.
Example:
Instrument Address = 1
Three scale factors sent
Scale factor 0 (
µ
S/m) is 10^8
Scale factor 1 (
µ
S/m Raw) is 10^8
Scale factor 2 (
µ
S/cm) is 10^6
To 2700 81H 77H
From 2700 81H 77H 30H 33H 30H 38H 30H 38H 30H 36H
‘0’ ‘3’ ‘0’ ‘8’ ‘0’ ‘8’ ‘0’ ‘6’
1.3.8 Send Sensor Status 74H/116
To 2700 ADDR CMD
Errors present:
From 2700
ADDR CMD MAX SNR ‘E’ E3 E2 E1 E0 CR