User's Manual

File : CS-SUP-MUTI-WTHERMAPP-E01.sxw
5 INFORMATION RELATIVE TO THE PROBES ASSOCIATED WITH THE
WAVETHERM MODULES
5.1 DALLAS Probes
5.1.1 Coding of temperatures for the DALLAS probe type DS18B20
These probes have a resolution of 12 bits and their value is coded on two bytes (MSB first)
Negative values are expressed in two's complements with addition of a sign.
MSB LSB MSB LSB
Most Significant Byte Leasr Significant Byte
b7 b6 b5 b4 b3 b2 b1 b0 b7 b6 b5 b4 b3 b2 b1 b0
S S S S 2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
2
-1
2
-2
2
-3
2
-4
Unit : Celsius degree (°C)
Bits [b7:b3] : sign bit.
Remark: The hexadecimal value 0x4FFF indicates the absence of a probe, or a connection error between
the module and the probe.
 Some temperature values:
Temperature Binary value (MSB First) Hexadecimal value
+125°C 0000 0111 1101 0000 0x07D0
+85°C 0000 0101 0101 0000 0x0550
+25°C 0000 0001 1001 0000 0x0190
0°C 0000 0000 0000 0000 0x0000
-10.125°C 1111 1111 0101 1110 0xFF5E
-55°C 1111 1100 1001 0000 0xFC90
5.1.2 Probe ID
The probe ID corresponds to a unique code attributed to each DALLAS temperature probe in the factory.
This code is composed of 8 bytes defined as follows:
MSByte LSByte
1 byte 6 bytes 1 byte
Family Code Serial n° (48 bits) CRC Code
The family code is used to distinguish between the probes used:
Probe DS18S20 : 0x10
Probe DS18B20 : 0x28
WaveTherm modules – application handbook page 15 of 65