11
i.
Baud
Rate
and
Default
Communication
Parameters
The
default
communication
parameters
for
the
MS2701E
transmitter
are
provided
in
Table
4
below.
If
necessary,
the
baud
rate
can
be
changed
using
Positions
1
and
2
of
Switch
2,
as
illustrated
in
Table
3.
Parameter
Value
Baud
Rate
19200
Data
Bits
8
Parity
Even
Stop
Bits
1
Table
4.
Default
Communication
Parameters
ii.
Device
Address
Up
to
32
MS2701E
transmitters
may
be
connected
in
a
multi
‐
drop
network
(“daisy
‐
chained”)
using
a
single
cable
run.
However,
each
transmitter
must
be
set
to
a
unique
device
address
to
avoid
conflicts.
This
is
done
using
Positions
3
through
7
of
Switch
2,
as
illustrated
in
Table
3.
CAUTION:
Be
sure
to
observe
the
appropriate
gas
group
rating
listed
on
page
3
for
stand
‐
alone
or
multi
‐
drop
operation.
iii.
Communication
Protocols
The
MS2701E
transmitter
offers
user
‐
selectable
RTU
or
ASCII
communication
protocols,
giving
the
unit
a
broader
range
of
compatibility.
The
communication
protocol
is
set
using
Position
8
of
Switch
2,
as
illustrated
in
Table
3.
iv.
Termination
Resistor
To
ensure
proper
operation,
the
RS
‐
485
network
must
be
terminated
properly
with
a
termination
resistor.
To
facilitate
this,
each
MS2701E
transmitter
has
a
built
‐
in
120
termination
resistor
that
can
be
switched
on
or
off
using
Position
10
of
Switch
2.
Once
all
units
have
been
installed,
be
sure
to
enable
the
termination
resistor
of
the
last
unit
in
the
network.
The
termination
resistors
of
all
other
transmitters
should
be
turned
off.
v.
Data
Registers
Table
5
lists
the
data
registers
of
the
MS2701E
transmitter.
No
Register
Address
Description
1
40001
Device
Status
2
40002
Device
Address
3
40003
Baud
Rate
4
40024
DAC
Value
5
40026
Probe
Switch
Setting
Table
5.
Modbus
Data
Registers