Instruction manual

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INM4840-5 Nov 2007
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1. INTRODUCTION
This instruction manual describes the procedures for installing,
connecting, checking and maintaining the MTL4840 HART
®
maintenance system, which is a simple interface between smart
devices in the field and HART instrument management software
running on a PC.
The following sections are outlined here.
Section 2 describes the system and the solutions available
Section 3 covers some safety aspects.
Section 4 deals with installing the backplanes
Section 5 describes installing and configuring the modules
Section 6 provides information on fault finding, and maintenance
Section 7 introduces software for the MTL4840 System.
See the MTL web site (www.mtl-inst.com) for the full specifications
of the MTL4840 system components and accessories, and of the
MTL4000 Series isolators.
2 DESCRIPTION
The MTL4840 HART Maintenance System enables a user to calibrate,
configure and maintain an entire network of 'smart' field devices from
a single workstation.
The key elements that make this possible are the MTL4841
communications module and the MTL4842 HART interface module.
These two modules provide the multiplexing for the individual field
devices, making each one addressable and identifiable.
The other important element is the terminal circuit board that simplifies
the interconnection of all these devices to the MTL484x modules. A
range of terminal boards and backplanes has been designed to
suit the more standard applications but custom versions can also be
designed to suit individual OEMs and their applications.
The MTL4841and MTL4842 use the compact plug-in style of the
MTL4000 Series of intrinsically safe isolating interface units. This
provides a quick and easy installation method onto the backplanes.
The system is organised in multiples of 16 (sixteen). The MTL4842
HART interface module can handle up to sixteen field devices. The
MTL4841 communications module is the next "layer", which can
manage up to sixteen of the MTL4842 modules, making a possible
total of 256 HART devices per MTL4841 module.
The MTL4841 modules are then connected via an RS485/RS232
converter to the host PC. Depending upon the management software
running on the PC, up to 31 of the MTL4841 modules could
be connected to it, making a potential device count of 7,936!
See Figure 2.1 for a diagram of this structure.
In addition to this standard configuration, the MTL4840 system will
support the multi-drop connection of HART devices. With up to fifteen
HART devices on a single loop, it is possible to expand the capacity
of each backplane (and consequently the system).
For intrinsically safe applications, consideration must be given to the
safety parameters for each loop. For further information, please refer
to MTL or your local representative.
2.1 General purpose or IS?
The MTL HART Management System can be used to control and
maintain field devices that are located in a safe area or a hazardous
areas.
For safe areas, HART Connection Units (HCUs - and their related
HMUs - see Section 2.3.1) provide the necessary terminals to connect
up to 16 field devices, with organised links to the MTL4842 interface
module.
Hazardous-area field devices can be handled through
backplane-mounted, IS isolating interfaces (BPxH). Having the
isolators mounted on a backplane dramatically reduces the amount of
hand wiring required and therefore reduces the number of potential
wiring errors. The hazardous-area wiring terminates on the isolating
modules, not the backplane, consequently the backplanes do not
need IS certification.
2.2 Generic or custom?
A range of generic connection units is available for both input and
output field-device wiring. These are not designed for any particular
DCS type and may be used universally.
The alternative is to choose a connection unit or backplane that
integrates with the type of DCS being used on the plant. The key
advantage of this method is the use of a DCS’s specific connector
type, which simplifies the wiring of the connection units into the system.
INM4840-5
Nov 2007
MTL4840 HART maintenance system
Figure 1.1 - BPHM64 HART backplane