MTL4850 two-way communications channel HART multiplexer

The MTL4850 HART multiplexer is used to create a two-way communications channel between numerous
items of HART-enabled field equipment and a plant asset-monitoring/control system. Each multiplexer module
can incorporate the HART data for up to 32 field channels into a single RS485 signal for onward linking to PC
based instrument management software, thereby simplifying the wiring and reducing the cost-per-channel.
The MTL4850 combines the functions of a HART modem, a power supply conditioner and all the necessary
signal-switching and addressing circuitry to multiplex the HART data. It provides a compact, convenient and

costeffective building block that can incorporated easily into both new and existing installations, especially as a partner
for Eaton’s MTL4500 range of intrinsic safety interfaces. It is the modern version of our popular MTL4840 range
and further simplifies the system.

MTL4850

The MTL4850 multiplexer enables the user to gain access to valuable HART data provided by modern field
devices in addition to the conventional 4/20mA loop signal provided by them. Many early process installation
projects around the world did not take advantage of the data from HART-capable devices at start-up, so the
MTL4850 offers a simple upgrade path to that data for asset management as well as the obvious live status and
configuration information of the field devices.
Most distributed control systems (DCS) now on the market incorporate the ability to pass HART communications
information on the analogue input and output channels, but many safety systems (SIS and F&G) do not.
Increasingly therefore, one of the main uses for the HART multiplexer is to provide HART communications for the
field instruments connected to safety systems. In such implementations, it is crucial that the HART multiplexer
does not interfere with the analogue loops of the safety system.