Emerson Rosemount 8600 Series, Справочное руководство, Страница: 63 / 130

55 Rosemount 8600 Vortex Flow Meter
Reference Manual
May 2019
Operation
00809-0100-4860, Rev BF
Pulse output test
A fixed frequency mode test that checks the integrity of the pulse loop. It tests that all
connections are good and that pulse output is running on the loop.
HART output
Refers to the connection of several flowmeters to a single communications transmission
line. Communication occurs digitally between a HART-based communicator or control
system and the flowmeters. Multidrop mode automatically deactivates the analog output
of the flowmeters. Using the HART communications protocol, up to 15 transmitters can be
connected on a single twisted pair of wires or over leased phone lines.
The use of a multidrop installation requires consideration of the update rate necessary from
each transmitter, the combination of transmitter models, and the length of the
transmission line. Multidrop installations are not recommended where intrinsic safety is a
requirement. Communication with the transmitters can be accomplished with
commercially available Bell 202 modems and a host implementing the HART protocol. Each
transmitter is identified by a unique address (1-15) and responds to the commands defined
in the HART protocol.
Figure 4 - 1 shows a typical multi-drop network. This figure is not intended as an installation
diagram. Contact Rosemount product support with specific requirements for multi-drop
applications.
Note
The Rosemount 8600D is set to poll address zero at the factory, allowing it to operate in the
standard point-to-point manner with a 4–20 mA output signal. To activate multidrop
communication, the transmitter poll address must be changed to a number between 1 and
15. This change deactivates the 4–20 mA analog output, setting it to 4 mA, and disables the
failure mode alarm signal.
FastKeys 1, 4, 2, 2, 2
FastKeys 1, 4, 2, 3
Figure 4 - 1. Typical Multidrop Network
Power
Supply
RS-232-C
Bell 202
Modem