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AMR SENSORS- Mode d'emploi / User guide version V1.2
Serial number
A-Field
Device version
Device type
Frame code
CI-Field
Short header
DATA-Field
Check Encryption
DIF
Primary VIF
Secondary VIF
Valeur
RSSI
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)
0x01000000 BCD coding. Read 00 00 00 10 (note: <1> refers to
0x03
0x19
0x7A
Access number 0x01
Status
0x00
0x00
Signature
0x00
0x2F2F
0x03
0xFD
0x3A
0xCE3C06
BF
Signal recep-
tion level
sensor No. 1, if <2>, it refers to sensor No. 2)
Product version
AD Converter
Short header frame
Increased incrementally upon each frame
Status of the product
No encryption
Always 0x2F2F (for encryption check)
Signed 24 bit data
Second extension of VIF
Dimensionless/no VIF
ADC or On-Off value. BCD Coding. Read 06 3C CE
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
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