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Modbus Addressing
The default Modbus slave address is 1. Care must be taken
to ensure that there are not two devices with the same
address. In such a case, an abnormal behavior of the whole
serial bus can occur. The master may not be able to
communicate with all present slaves on the bus. A change to
the Modbus address will take effect immediately.
Modbus Baud Rate and Parity
Baud rate and parity can be set through both the user
interface and the Modbus port. The changes do not take
effect until the next power cycle reset or soft reset, but they
will be reported via their respective registers, or on the user
interface. A soft reset can be requested by writing a 1 to the
Configuration Reset Register 402.
For example, assume that the unit is configured to
communicate at 19.2k. A read of register 432, Modbus Baud
Rate Code, will return a "4" for 19.2k baud. If a subsequent
write of "7" is made to register 432, to change the baud rate
to 115.2k, the unit will return "7" when register 432 is read,
but continue to communicate at 19.2k baud until either
power cycle reset or soft reset is asserted. Once the unit
receives either a power cycle reset, or a soft reset is
asserted, the unit will communicate at 115.2k baud and will
return "7" on reads to register 432. The same behaviors
apply to the parity settings as well.
0x2B/0x0E Read Device Identification Get Device
Identity (43/14) Details
Device ID codes 1, 2 and 4 are implemented. Device ID code
3 (extended info) is not implemented.
Object IDs
0
VendorName
1
ProductCode
2
MajorMinorRevision
3
VendorURL
4
ProductName
5
ModelName
6
UserApplicationName
C440/XTOE Electronic Overload Relay, Modbus MN04210004E—March 2011 www.eaton.com
C440-COM-ADP Communication Module
Modbus Command Register (400)
Command Codes
Command
Clear motor run hours
Delete last fault from queue
Comm watch dog enable
Comm watch dog disable
Fault reset
Clear motor start count
Force ground fault
Remote off
Auxiliary relay reset
Note: Command register will clear after being written to.
Configuration Reset Register (402)
Reset Codes
Action
Power cycle reset
Factory reset
Range Checking
Many configuration parameters are range checked. When
implemented, if value is greater than the maximum allowed
value, the parameter is set to its maximum. Likewise, if a
parameter is set to a value less than its minimum value, the
parameter will be set to its minimum value. For function
code 0x06, when the range checking causes a value to be
different from what is requested to be written, the Modbus
response to the 0x06 command returns the requested value,
not what was actually written. A subsequent read of this
parameter will return the actual value that it was set to.
Code (Hex)
66H
77H
88H
99H
AAH
BBH
CCH
DDH
EEH
Reset Code
1
2
17
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