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MT100 Multipoint Flow Meter
HART Operation
HART (Highway Addressable Remote Transducer) is a communication protocol that superimposes a low level digital data signal on a 4-20 mA
current loop. The primary function of the instrument's HART interface is to present process data via process data commands 1, 3 and 9.
The MT100 does not implement the HART Burst mode. A HART master that supports HART 7.0 and higher is required. If using a HART
communicator, a unit that supports HART 7.0 or higher is required (i.e. Emerson 475 Communicator). Connect the installation
(factory/plant) HART wiring to the instrument as described in HART, page 27.
Process Data Operation
The MT100 implements HART 7.0 while maintaining compatibility with earlier versions of the HART protocol. However, HART commands 1
and 3 have been simplified to only report the primary variable Flow. Use command 9 to access the full suite of available dynamic variables
including temperature, totalizer, and others.
MT100 HART Process Data Organization
This section describes how the instrument process data is organized under the HART command 9. For details on command 9 see the
HART Specification "Universal Commands Specification" HCF_SPEC-127, Revision 7.1 and the command 9 description on page 49.
MT100 Process Variable Slots
Table 5
below lists the instrument's 6 process variables that are read by HART command 9, with each process variable assigned a slot number.
Not all the variables described in this section are available in all configurations of the flow meter. For example, the Flow Totalizer may be
turned on or off.
The process variables include 3 flow classes or types of which only one class of flow is active at a time.
Slot #
0
1
2
3
4
5
Note: 1. Only one active at a time.
Primary Variable Classifications
The instrument can provide flow data in unit types that span several HART classifications. Commands 50 and 51 are used to read and set,
respectively, which flow variable will be mapped to the primary variable. The PV device variable classification can only be one of the following:
●
0: Volumetric Flow
●
2: Mass Flow
●
4: Velocity Flow
Since only PV is used in this manner, command 50 returns 250 for SV, TV, and QV. The setting of the device variable classification determines
which class of flow-related variables is valid, and therefore displayed as implemented when variable slots are read by command 9.
Device Description Files
A Device Description (DD) file lets the HART handheld or host software application fully configure any HART device for which it has a DD
installed. The MT100 DD files are available for download (pending) from the HART Communication Foundation website:
http://www.hartcommproduct.com/inventory2/index.php?action=list
Browse by Member (FCI – Fluid Components International) to find the instrument's files under device type: a679 (MT100 Series)
Refer to the following HART Communication Foundation web page for guidelines on using a DD file:
http://www.hartcommproduct.com/using_dd.html
Fluid Components International LLC
Table 5 – MT100 HART Process Variables
Process Variable
HART Variable Code
Description
Volumetric Flow
Primary Variable
1
Volume (Totalizer)
Secondary Variable
Mass Flow
Primary Variable
1
Mass (Totalizer)
Secondary Variable
Velocity Flow
Primary Variable
1
Temperature
Tertiary Variable
Device Variable Code
0
1
2
3
4
5
OPERATION
Device Variable
Classification
66
68
72
71
67
64
43
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Troubleshooting
