Effective Date: 2/04
IL17574C
Page 5-1
IQ 300
Effective Date: 2/04
Page 5-1
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SECTION 5: NETWORK COMMUNICATION PROTOCOLS
5.1
MODBUS RS485 NETWORK
The IQ 330M can be accessed by MODBUS messages through a RS485 interface.
In order to do this properly please refer to IL 17384, Part A and Part B: IMPACC
Communications Standard, EATON | Cutler-Hammer “Modicon MODBUS Protocol”
and IL 66A7508H01 Instructions for the mMINT MODBUS Translator Module.
The following simplified rules apply to a given system consisting of master and slave
devices. For more complex configurations please refer to standard MODBUS RTU
wiring specification rules for the RS485 network.
The recommended MODBUS cable has twisted-pair wires (24AWG stranded 7x32
conductors with PVC insulation) having an aluminum/mylar foil shield with drain
wire.
The maximum system capacity is 4,000 feet of communications cable and 32
devices on the MODBUS RTU network.
Make sure the twisted-pair wire is recommended for MODBUS RTU network use.
Use shielded twisted-pair wire to connect each slave to the MODBUS RTU network,
daisy-chain style. The polarity of the twisted pair is critically important, MODPIN1 is
MOD(A) and MODPIN2 is MOD(B).
Tie the communication cable shield to ground only once at the MODBUS master
device. If there are more than one remote MODBUS compatible device cabled to
the master device, tie the communication cable shields together but
do not
connect
to ground.
5.2
OVERVIEW
The contents of MODBUS registers are product objects (e.g. Ia – phase A current).
There is a single register map for all Eaton | Cutler-Hammer IQ products. Conse-
quently, the objects listed in the following tables are identical registers called out by
the mMINT. The IQ 330M supports the fixed values only and occupy two registers.
See table 5.1.