I.L. 66A7508H05
Page 5
Effective September 2003
Table 5: RS485 Baud Rate Switches (Diagnostics)
5.9 Modbus
121
Ω
Termination Dip Switch (SW3)
This switch should be moved to the “ON” position only when it
is the last unit in a chain of units or if it is a single unit.
6.0 NETWORK COMMUNICATION PROTOCOLS
The lower INCOM communication network for the mMINT is
based on a master-slave protocol. The mMINT is a master on
the INCOM network.
In order to satisfy the mMINT communications needs, please
see Reference Materials:
IL17384 - Part A:
IMPACC Communications Standard,
EATON, Cutler-Hammer. Specific product profiles are located
in the other Part sections.
http://www.cutler-hammer.eaton.com
, then search on
17384
.
“Modicon Modbus Protocol”,
http://www.modicon.com/techpubs/toc7.html
6.1 Overview
The contents of Modbus registers are INCOM product objects
(e.g. I
A
– phase A current). The mMINT ensures that unique
objects reside in identical registers independent of INCOM
product. Consequently, for all INCOM products there is a
single register map of objects. See
Table
7
or
Table 8
.
INCOM objects occupy two (2) registers except for certain
energy – real and reactive – objects. These energy objects
occupy four (4) registers. The mMINT can support a maximum
of 122 registers within a single Modbus transaction.
The mMINT is transparent to the Modbus master and responds
to every address of INCOM products attached to it. In its
default configured state, INCOM product addresses are
Modbus network addresses. The mMINT can be configured to
route the Modbus address to a different INCOM product
address or an INCOM sub-network product address. See
Section 6.5.
An upgrade has been incorporated to allow the mMINT to
communicate with Modbus masters which can only access to
register 9999. Registers previously assigned above 9999 have
been assigned dual access, both at the original register (to
provide compatibility) and at a new register assignment below
9999. The format is given as low/high register numbers
followed by (low
16
/high
16
Modbus addresses), for example:
4xxxx/4yyyyy (XXXX+1
16
/YYYY+1
16
). See
Table 13
.
Only the RTU communications mode is recognized by the
mMINT.
6.2 Function
Codes
The mMINT responds to a limited number of Modbus function
codes. These are function codes 03, 04, 08 and 16 (10
16
).
6.3 Block of Registers
A block of registers (from the register column of
Table
7
or
Table 8
) can be established for each INCOM product attached
to a mMINT.
Function code 16 (10
16
) is used to load the object assignments
for the block of registers. The block assignments are stored
beginning at register 41001/420481 (03E8
16
/5000
16
). Only the
first object register is assigned within the block of registers. For
example, although object I
A
occupies registers 404611 (1202
16
)
and 404612 (1203
16
), only 404611 (1202
16
) is loaded into the
block of assignment registers. Verification of this block of
assignment registers can be read from the mMINT by a read
function code 03 or 04 from these 41001/420481
(03E8
16
/5000
16
) registers.
Data pertaining to the objects configured in the block of
assignment registers is mapped into registers starting at
41201/420737 (04B0
16
/5100
16
) and continuing in successive
order for each object assigned. The number of objects and
their placement order in this data block of registers is
dependent on the configuration of the block of assignment
registers. The total number of data block of registers is limited
to 100. Note that an object can occupy one, two or four
registers.
The data can be obtained from the data block of registers by a
read function code 03 or 04. The address of the starting object
must be aligned with a starting address of an object within the
data block of registers. The number of registers to obtain must
align with an ending address of an object within the data block
of registers.
6.4 Register Access Configurations
Non-volatile register 42001/425345 (07D0
16
/6300
16
) is used to
configure the mMINT to respond to a group of data objects, of
which some objects are invalid within that group. When
non-zero (factory default value), any attempt to access a group
of data objects which contain an invalid object will result in an
illegal data object exception code 02. See Section 6.10.
When register 42001/425345 (07D0
16
/6300
16
) is set to zero,
however, the mMINT will respond to a group of objects with
data contained in the valid objects of the group along with an
illegal value, if available else 0000
16
, data contained in the
invalid objects.
Non-volatile register 42002/425346 (07D1
16
/6301
16
) is used to
configure 32-bit IEEE floating point word order. When
non-zero (factory default), the floating point low order word is
first in the Modbus register space.
When register 42002/425346 (07D1
16
/6301
16
) is set to zero,
however, the floating point high order word is first in the
Modbus register space.
Baud
SW2-1
SW2-2
SW2-3
Addr. 247 or 248
OPEN
X
X
Normal
CLOSE
X
X
