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Axetris AG
LGD Compact Operating & Integration Instructions; Rev. D
29/46
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)
Description
Data Type
7B 4D Begin of packet: open brace {M
2 Bytes
10 00 Packet size = 16
Unsigned Integer 16 Bit
00 00 Error code
2 Bytes
28 54 EE 45
Concentration gas 1
= 7626.52
1 Float
(single Precision)
00 00 00 00 zeros to reach packet size multiple of 8
4 Bytes
79
Checksum
1 Byte
7D End of packet: close brace }
1 Byte
Table 12 For Applications with 2 target gases (One measurement packet contains 24 Bytes)
Bytes (Hex)
Description
Data Type
7B 4D Begin of packet: open brace {M
2 Bytes
18 00 Packet size = 24
Unsigned Integer 16 Bit
00 00 Error code
2 Bytes
05 71 47 42
Concentration gas 1
= 49.9
ppm
1 Float
(single Precision)
03 BC 4D 46
Concentration gas 2
= 13167
ppm abs. humid.
1 Float
(single Precision)
E0 AB F4 41
Temperature [°C]
= 30.6 °C
1 Float
(single Precision)
00 00 00 00 zeros to reach packet size multiple of 8
4 Bytes
0F
Checksum
1 Byte
7D End of packet close brace }
1 Byte
Floats are coded based on IEEE754 - tools can be used under
http://www.binaryconvert.com/convert_float.html
to convert them.
(Bytes order should be reverted “Little endian.”)