Copyright © Romilly Bowden 2000 - 2011.
If you need to communicate with more than one or two HART networks, you may want to use a HART multiplexer. These include the modem function, generating and receiving the HART FSK signal, and handling the details of the HART protocol for several connected HART loops. They provide a single host serial interface (RS232 or RS485) to connect to your host PC or other computer.
Several manufacturers offer these products. However, there are significant variations between the available products, for example:
When choosing a HART multiplexer, you need to take great care to ensure that the structure and functionality is appropriate for your application, and that the communication speed will be sufficient. In particular, check the number of HART modems - a single modem scanning all channels can only read about one channel per second.
These manufacturers may have other similar products available. Always ask them for the latest information. The brief descriptions given here do not describe the detailed capabilities of each multiplexer, and are not sufficient for you to make a final selection.
Eurotech (was Arcom) HTNodeA DIN-rail mounting unit, providing 1 HART channel. Multidrop up to 15 devices. Host communication via 1 RS-232 port, with Modbus slave RTU protocol.
3 Clifton Court
Cambridge CB1 7BN
Web site: www.eurotech-ltd.co.uk
Telephone: +44 1223 403410
Fax: +44 1223 410457
Eurotech (was Arcom) HTMuxA modular system in a rack-mounting cardframe. 8 HART channels per card. Multidrop subject to overall number of devices. Host communication via 2 RS-232 ports, with Modbus slave RTU protocol, or Ethernet.
Eurotech (was Arcom) H-PortA DIN-rail mounting unit. 32 HART channels. Host communication via an RS-485 port, still using the HART protocol but at higher speed.
Cimat CIM 53104 HART channels. Each channel has its own HART modem and supports multidrop up to 15 devices. 3 RS485 host ports with Modbus slave (RTU or ASCII) protocol. Eurocard format.
More information here.
|CIM Advanced Technology Limited|
7 Beeches Close
Leicestershire LE16 9UQ
Web site: www.geocities.com/SiliconValley/Lab/7487
Telephone/fax: +44 1858 881388
Elcon HART INTERFACE SOLUTIONS™A wide range of I/O termination panels, incorporating the 2700-MUX HART multiplexer module. HART host communication by RS485 port, with proprietary "HART-like" protocol. Each 2700-MUX connects to 32 HART channels. Multidrop up to 15 devices per channel. Optional IS barriers on field I/O side. Analogue signals passed to DCS or PLC, via HART filters for those which need them.
|Elcon Instruments SRL|
Via Velasca, 36A
20059 Vimercate (MI)
Web site: www.elcon_inst.com
Telephone: +39 39 62921
Fax: +39 39 608 5331
Elcon Intrinsic Safety Ltd.
Co. Durham DL5 6XZ
Telephone: +44 1325 314 455
Fax: +44 1325 314 456
Pepperl+FuchsModular I/O subsystem, incorporating the KFD2-HMM-16 master HART modem/multiplexer and up to 15 KFD0-HMS-16 slave multiplexers. Each multiplexer connects to 16 HART loops. Host communication via RS-485 port with proprietary "HART-like" protocol. IS barriers on field I/O side. Analogue signals passed to DCS or PLC.
|Pepperl+Fuchs GB Ltd.|
77 Riponden Road
Lancashire OL1 4EL
Web site: www.gb.pepperl-fuchs.com
Telephone: +44 161 633 6431
Fax: +44 161 624 6537
MTLModular I/O subsystem, incorporating the MTL4841 communications module and MTL4842 HART interface modules. Each MTL4842 connects to 16 HART loops. Host communication via RS-485 port with proprietary protocol. Optional IS barriers on field side. Analogue signals passed to DCS or PLC.
|Measurement Technology Ltd.|
Bedfordshire LU1 3JJ
Web site: www.mtl-inst.com
Telephone: +44 1582 723633
Fax: +44 1582 422283
RAP SystemsDIGI-HART-8M 8-channel Hart interface module. DIN rail mounted. RS-232/422/485 or ethernet TCP/IP host ports. HART modem or HART-to-Modbus conversion modes. Automatic polling or programmed operation. More information here.
RAP Systems Ltd.|
20 Holbeck Avenue
Web site: www.rapsystems.co.uk
Telephone: +44 3333 440081
Fax: +44 3333 440082