Emerson MVS205 Safe Use Instructions page 6

Safe Use Instructions — MVS205
ROC or FloBoss using a serial 4-wire EIA-485
(RS-485) connection.
The four wires should be a minimum size of
22 AWG and a maximum length of 605
meters.
Table 1. MVS Interface Circuit Terminals
Terminal
Earth CS
Earth DR
COMM A
COMM B
RTD REF
RTD +
RTD —
RTD RET
PWR +
PWR —
The terminals in the MVS205 head are labeled
the same as the terminals on the MVS
terminal block in the ROC or FloBoss. Connect
the ROC or FloBoss and Remote MVS
terminals one to one: A to A, B to B, "+" to
"+", and "—" to "—".
Do not reverse polarity of the power wires (+
and —) while wiring the MVS unit.
For the FB107, run four wires from the

terminal block on the FB107 MVS module
to the MVS sensor.
 For the ROC800-Series, run four wires
from the terminal block on the ROC800
MVS or MVS IO module to the MVS
sensor.
In all cases, make connections by baring the
end (6 mm maximum) of the wire, inserting
the bared end into the clamp beneath the
termination screw, and then tightening the
screw to 0.25 N-m.
Pay close attention. Do not reverse the power
wires. Always make these connections after
removing power from the ROC or FloBoss.
Double-check for proper orientation before
applying power. If the connections are
reversed and you apply power, you can
damage both the MVS and the ROC or FloBoss
processor board.
7. Connect the Remote MVS to a suitable earth
ground per applicable codes and standards.
Two means of grounding are available on the
unit: internal and external. Refer to Figure 2
for the location of the external ground.
All earth grounds must have an earth to
ground rod or grid impedance of 25 ohms or
Usage
Earth Case
Earth Drain
RX/TX+
RX/TX —
RTD REF
RTD +
RTD —
RTD RET
Power +
Power —
less, as measured with a ground system
tester. The grounding conductor should have
a resistance of 1 ohm or less between the
MVS205 sensor head ground and the earth
ground rod or grid.
Note: Refer to the MVS205 Case Isolation
Installation Sheet (part
D301641X012) for case isolation and
grounding information.
To safeguard against lightning strikes, install a
surge suppression device at the service
disconnect on DC voltage source.
8. Use an external three- or four-wire RTD to
sense the process temperature. The RTD
sensor is connected directly to MVS sensor's
interface circuit board. A separate RTD cable
assembly is required for the connection. Refer
to Table 1 for the terminal descriptions.
Set the address of each MVS prior to final
wiring of multiple MVS devices. For proper
operation of multiple MVS devices, each MVS
device must have a unique address. The
FloBoss 107 supports a single MVS module
that connects with up to six MVS devices; the
ROC800-Series supports up to two modules,
each of which connects with up to six MVS
devices.
 Connect the ROC/FloBoss to a computer
running ROCLINK 800 software.

Select Configure > I/O > MVS Sensor.

Navigate to the MVS screen associated
with the MVS being addressed.
 Enter the unique number in the Address
field. Do not use addresses 0 or 240.

Click Apply or Save to save your changes.
®
9. Use Sealtite (or a similar product) to seal the
conduit path from the Remote MVS to the
ROC or FloBoss. Unarmored cable may be
used if installed in conduit and have seals per
hazardous installation practices. Before you
calibrate and place the MVS205 sensor into
operation you must configure it using
ROCLINK 800 software. Connect the PC
running ROCLINK 800 to the LOI port of the
flow computer in order to transfer
configuration data into the MVS205 sensor.
The firmware of the MVS sensor contains
default values for all parameters. If the default
is acceptable for your application, leave is as
found. Perform any adjustments to the MVS
unit using ROCLINK 800 configuration
software. Refer to the ROCLINK 800
Configuration Software User Manual for your
applicable device.
Part D301205X012
Page 4