1569
‐
PT060EE1
Rev.
7
Page
55
of
62
6.4
Bi-directional modality with MODBUS protocol
The
RTU
version
of
MODBUS
is
used.
Received
and
transmitted
frame
structure.
General
frame
structure
is
as
follows:
ADRESS
FUNCTION
DATA
CHECK
8
bits
8
bits
N
x
8
bits
2
x
8
bits
ADDRESS
FUNCTION
DATA
CHECK
8
bits
8
bits
N
x
8
bits
2
x
8
bits
ADDRESS
8
bit
defining
the
slave
address
and
ranging
from
1
to
32
FUNCTION
8
bit
defining
the
required
function.
The
functions
supported
by
T060E
are
the
following
Code
03
Read
Holding
Registers
Code
05
Force
Single
Coil
DATA
All
data
relevant
to
the
specific
function
CHECK
CRC
‐
16
(Cyclic
Redundancy
Check)
frame
validation
Exception
responses
When
T060E
receives
a
request
involving
illegal
functions
or
illegal
data
an
exception
response
is
generated
containing
address,
function
code,
error
code
and
checksum.
To
indicate
that
the
response
is
a
notification
of
an
error,
the
high
order
bit
of
the
function
code
is
set
to
“1”.
Supported
error
code
are:
01
Illegal
function.
The
message
function
received
is
not
an
allowable
action
for
the
addressed
slave.
02
Illegal
data
address.
The
address
referenced
in
the
data
field
is
not
an
allowable
address
in
the
address
slave
location
03
Illegal
data
value.
The
value
referenced
in
the
data
field
is
not
allowable
in
the
addressed
slave
location
T060E
supported
functions
For
a
complete
description
of
MODBUS
available
functions,
please
refer
to
detailed
MODBUS
documentation.
Function
03
‐
Read
Holding
Registers
Allows
the
host
to
obtain
the
binary
value
of
the
content
of
T060E
registers
All
registers
can
be
transferred
in
a
single
read
request.
The
below
example
reads
registers
0
through
2
from
slave
01:
ADDR
FUNC
START
REG
HI
START
ERG
LOW
#
OF
ERG
HI
#
OF
ERG
LOW
CHECK
01
03
00
00
00
03
05
CB
Slave
answer
is
as
follows:
ADDR
FUNC
BYTE
COUNT
REG
0
HI
REG
0
LOW
REG
1
HI
REG
1
LOW
REG
2
HI
REG
2
LOW
CHECK
01
03
06
00
0F
00
00
01
C0
74
B4
Value
of
register
0
is
15,
register
1
is
0
and
register
2
is
448.
