A.6 HART variable data record
The I/O module supports a maximum of 4 HART variables per channel in enabled HART
operation. These variables are read cyclically, provided they are supported by the connected
eld device.
These 32 HART variables are available to be read in HART variable data record 121.
Each HART variable consists of a 4-byte real value and 1-byte quality code.
In IO redundancy mode, the HART variables are only updated if the HART interface is on the
corresponding module/channel. The channel may not be in standby mode. If the HART interface
is on the partner module/partner channel, the corresponding HART variable is initialized (quality
code = 0x37).
Structure of the HART variable data record
Byte Meaning
Channel 0
0…3 Value Primary Variable (PV)
4 Quality Code
5…8 Value Secondary Variable (SV)
9 Quality Code
10…13 Value Tertiary Variable (TV)
14 Quality Code
15…18 Value Quaternary Variable (QV)
19 Quality Code
Channel 1
20…39 HART variables same as for channel 0
Channel 2
40…59 HART variables same as for channel 0
Channel 3
60…79 HART variables same as for channel 0
Channel 4
80...99 HART variables same as for channel 0
Channel 5
100...119 HART variables same as for channel 0
Channel 6
120...139 HART variables same as for channel 0
Channel 7
140...159 HART variables same as for channel 0
If HART is not enabled or the respective HART variable is not supplied from the connected eld
device, the corresponding variable = 0 and the QC = 0x37 (initialization value from the analog
module).
HART operating data records
A.6 HART variable data record
F-AI 8xI 2-/4-wire HART HA
Equipment Manual, 09/2021, A5E50557845-AA 105
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