Tracerco Optimus T221, Operation Manual

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MD1064 Rev. F 21 of 32
6.2.1.9 Device Variables 79-150 – Build Up per Stage
Optimus™ is capable of providing an up to date indication of solids build up on the vessel
wall for stages that are in the gas phase. These Device Variables report the amount of
build-up present for each stage.
Device Variable 79 represents build up on Stage 1, Device Variable 80 represents build up
on Stage 2 and so on.
If a particular stage does not exist for the current device configuration then a value of 0
is returned.
6.2.2 Dynamic Variables
The Optimus™ control module allows access to all four of the HART 7 dynamic variables
(PV, SV, TV and QV). The primary variable (PV) has a fixed mapping to Device Variable 0,
the Process Level. The secondary (SV), tertiary (TV) and quaternary (QV) variables can
be remapped to any of the Optimus™ device variables. This can be achieved using HART
7 Common Practice Command #51. Table 6 shows the default dynamic variable
assignments.
Dynamic
Variable Device
Variable Name Description Unit Code
PV 0 Process Level Calculated process level
resistant to solid build up
deposits on the vessel wall
and variations in pressure. Percent
(57)
SV 1 Maximum
Build Up The value of the stage that is
reporting the most build up. cm (48)
TV 2 Elevation of
Maximum
Build Up The elevation of the centre of
the stage that is reporting the
most build up. Percent
(57)
QV 4 Average Gas
Phase Build
Up The average build-up of all
stages currently in the gas
phase. cm (48)
Table 6. Default dynamic variable assignments.
6.2.3 Status Information
The HART 7 communication protocol provides standard methods of reporting device status
information. The T221 control module returns 9 bytes (0
– 8) of Additional Device Status
information through Command 48 as per the HART 7 specification.
6.2.3.1 Device Status
The following three bits may have associated status bits available in Command 48.
• Bit 7, Device Malfunction, indicates that the Optimus™ control module has detected
a serious error or failure that compromises device operation.