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Very long commands > 64 bytes
For very long commands (> 64 bytes) it's important that the packet transmission lasts a certain amount of time.
AXAG recommends adding a waiting time of 5 ms every 8 bytes during transmission, to lengthen the
transmission time and avoid problems. Every valid transmission to the device will be acknowledged.
3.3 Measurement data format
After connecting the power supply, the device sends a version packet (containing 64 bytes) and then starts
sending measurement packets continuously, roughly every second. All float and integer values have the little
endian format (according to Norm IEEE 754).
For different device types the measurement packets have the following format:
Table 11 For Applications with 1 target gas (One measurement packet contains 16 Bytes)
Bytes (Hex)
7B 4D
10 00
00 00
28 54 EE 45
00 00 00 00
79
7D
Table 12 For Applications with 2 target gases (One measurement packet contains 24 Bytes)
Bytes (Hex)
7B 4D
18 00
00 00
05 71 47 42
03 BC 4D 46
E0 AB F4 41
00 00 00 00
0F
7D
Floats are coded based on IEEE754 - tools can be used under
http://www.binaryconvert.com/convert_float.html
(Bytes order should be reverted "Little endian.")
Axetris AG
LGD Compact Operating & Integration Instructions; Rev. D
Description
Begin of packet: open brace {M
Packet size = 16
Error code
Concentration gas 1
= 7626.52
zeros to reach packet size multiple of 8
Checksum
End of packet: close brace }
Description
Begin of packet: open brace {M
Packet size = 24
Error code
Concentration gas 1
= 49.9 ppm
Concentration gas 2
= 13167 ppm abs. humid.
Temperature [°C]
= 30.6 °C
zeros to reach packet size multiple of 8
Checksum
End of packet close brace }
2 Bytes
Unsigned Integer 16 Bit
2 Bytes
1 Float
(single Precision)
4 Bytes
1 Byte
1 Byte
2 Bytes
Unsigned Integer 16 Bit
2 Bytes
1 Float
(single Precision)
1 Float
(single Precision)
1 Float
(single Precision)
4 Bytes
1 Byte
1 Byte
to convert them.
Data Type
Data Type
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