AMR SENSORS- Mode d’emploi / User guide version V1.2
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A-Field
Serial number
0x01000000 BCD coding. Read 00 00 00 10 (note: <1> refers to
sensor No. 1, if <2>, it refers to sensor No. 2)
Device version
0x03
Product version
Device type
0x19
AD Converter
Frame code
CI-Field
0x7A
Short header frame
DATA-Field
Short header
Access number 0x01
Increased incrementally upon each frame
Status
0x00
Status of the product
Signature
0x00
No encryption
0x00
Check Encryption
0x2F2F
Always 0x2F2F (for encryption check)
DIF
0x03
Signed 24 bit data
Primary VIF
0xFD
Second extension of VIF
Secondary VIF
0x3A
Dimensionless/no VIF
Valeur
0xCE3C06
ADC or On-Off value. BCD Coding. Read 06 3C CE
RSSI
Signal recep-
tion level
BF
RSSI of the frame received: RSSI value = -125 + (x
*0.5), namely, in this example BF = 191, RSSI =
-125 + (191*0.5) = -29.5 dBm
5.1.4 Decoding sensor value
In the case of an I/O sensor
, the value is expressed using 0 or 1:
•
Value 0 = contact open
•
Value 1 = contact closed
•
In the frame example provided above, the value is 0x063CCE.
In the case of an analogue sensor (4-20 mA version)
, the formula to be applied is as follows: I = value x 2.048/(220 x 99.8)
Procedure:
•
Convert the value of the frame into a decimal: 0 x 063CCE = 408782 as a decimal
•
Apply the following formula: I= 408782 x 2.048/(220x 99.8)= 0.008 A (or 8 mA)
•
The result is:
8 mA
If, in our example, our sensor is a temperature sensor that measures a range from -40°C to +80°C, in that case 4 mA corresponds to -40°C and
20 mA corresponds to +80°C (note: we are working from the principle that the sensor used has a linear response curve).
To convert the value in mA into a temperature, you have to apply the following formula:
T° =-40+((I-4) x 120/16)
Result: -40 + ((8-4) x 120/16) = -10°C
Note:
•
I = the value in mA
•
-40 = the offset to be applied
•
120 = the spread of the temperature range (from -40 to +80)
•
16 = the range of the current measurement (from 4 to 20 mA)
