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1. When do I use HART Filters?
1. When do I use HART Filters? HART filters may be necessary for certain systems for the following reasons:
There are two ways to use HART filters;
Note that when an individual HART filter is used, the Elcon panel must be connected to the field side of the HART filter. Pepperl+Fuchs Elcon recommends HART filters for any HART output signal (valve positioners). DCS systems from Bailey, Fischer and Porter, Honeywell, Foxboro, and Emerson may require HART filters. Consult with the valve positioner or I/P supplier to learn if filters are required for a specific control system or field device. CAUTION: HART filters are only for use with output signals. Transmitters will not function when connected to a channel with a HART filter. Analog Inputs HART filters for Analog inputs are generally not required for any of the DCS or Safety Shutdown System solutions. There are some cases with PLC interfaces, where the PLC I/O card can have a very fast response time and detect the HART current modulation as a Process Variable change. Please contact P+F directly for a solution if this application arises. 2. When do I use Fuses? 3. When do I wire in Parallel? Note: It is not possible to use HART filters that are integrated into the P+F Elcon panel when wiring in parallel. 4. How do I establish a Parallel Connection? Connecting to marshalling terminals. Using either the existing terminals (with wiring in parallel) or for cleaner wiring "1 in 2 Out" terminals. Specific signal pairs containing HART signals can be connected to Elcon external panels via screw terminals or DCS cable (depending on the system). 5. When do I wire in Series? Note: Although the panel is wired in series, the HART multiplexer circuitry is in parallel with the 4-20 mA signals, and removing the multiplexer will not disrupt the 4-20mA circuit. 6. What are the advantages and disadvantages of connecting the Mux2700 in series and in parallel? The parallel connection has the advantage that the mux panel can be removed, or added without disturbing the field wiring and DCS. This makes the parallel connection useful for retrofit applications. The disadvantages of the parallel connection are that the customer will have to usually add a second wire underneath the field wiring terminal blocks in order to make the connection to the mux panel, and they cannot use the integrated HART filter option on our panels as this can only be implemented using a series wiring technique. Series wiring has the advantages that the HART filters can be used, and there is only one wire per terminal block, which is usually more acceptable to the plant level personnel. The disadvantages of series wiring installations are that it is more difficult to install on retrofit applications, and the panels once installed cannot be removed without disrupting the system. Top There is a large range of P+F Elcon HART termination panel solutions for the majority of DCS systems on the market today. Termination panel replacement solutions are typically used for new projects, and upgrades where the DCS is being purchased with a P+F Elcon panel as the field-wiring interface. Custom termination panels can also be used to replace existing DCS termination panels to add HART multiplexers to an existing system. Using a custom solution to provide HART multiplexer connectivity to a DCS has the following advantages:
8. What is the complete list of DCS / ESD Systems for which P+F Elcon have customized solutions?
9. Does the HART multiplexer interfere with the DCS communications? This family of HART interfaces have a proven track record in hundreds of installations worldwide, and have been designed from the ground up to provide connectivity between AMS Device Manager and HART instruments in the field without compromising the integrity of the 4-20 mA signal used by the DCS or PLC. HIS is –by far – the most elegant, cost-effective and concise solution for HART connectivity. The fundamental design premise for the HART Multiplexer is the notion that the control and maintenance plant environments are two separate entities. Elcon’s termination panels and HART multiplexers are designed to provide maintenance personnel with the HART information they need without compromising the integrity of the control system. The termination panels are passive in nature, just providing a connection path between the inputs and the outputs. The HART muxes are connected to the circuit in parallel, and provide three port isolation as well as dual capacitors for high integrity. While using any of our solutions, customers can remove or install the HART multiplexer while the control loops are operational, without causing any disturbance. Additionally, the HART multiplexer can fail while installed, without altering the 4-20 mA signal. There are a couple of technical documents that further document this design criterion. First, the 2700 manual, pages 4, 6-8 (sections 3.1 - 3.6) describe the mux functionality and interface to the 4-20 mA signal. Second, the schematic of the DIN rail termination panels show that the mux is connected in parallel, no matter how the field wiring is done. I have enclosed the schematic of our Minimux panel as an example. 10. How do I build a network of Elcon Mux2700’s? Up to 31 multiplexers can be multidropped to support a single network of up to 992 devices on a single PC serial port. AMS Device Manager with the HART Multiplexer Interface communicates with HART devices via a connection from the RS232 serial port on the AMS Device Manager PC to a RS232/RS485 converter. From the converter, an RS485 line is run to the multiplexer that receives device information from either a cable or parallel wires to the termination panel. 11. How do I connect more than 992 devices to an AMS system? Each Elcon Multiplexer provides communication to 32 HART devices. Elcon Multiplexers—up to 31—can be multi-dropped to support a single network with a maximum of 992 field instruments. Multiple Elcon Multiplexers are connected in a daisy chain formation. For larger installations, additional networks can be built using other serial ports on the PC workstation. 12. What is a Universal Cable? Only one type of wiring connection can be used for each HART Multiplexer Interface. The Universal Cable allows you to connect the HART Multiplexer Interface to any DCS I/O terminal panel. Each Universal Cable has a DB37 pin connector for connection to the HART Multiplexer Interface. On the opposite end, 16 labeled pairs of color-coded wire provide connection to your termination panel. The cable may be up to 50 feet (15 meters) and is also available in 10 feet (3 meters) and 30 feet (9 meters) segments. Unused pairs of wire should be capped off or cut off to avoid EMI problems. 13. What is AMS Device Manager? The AMS Suite:
Intelligent Device Manager application and the associated SNAP-ON applications are a suite of software solutions for streamlining all maintenance activities relative to instrumentation and valves in a process plant.
AMS Device Manager gives users online access to process instrumentation and automatically captures all instrument maintenance information.
AMS Device Manager is a single tool for device configuration, documentation, calibration management and diagnostics.
For more information on AMS Device Manager, please visit the AMS Device
Manager website at:
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