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MVI56-MCM
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ControlLogix Platform
Configuration as a Modbus Master
Modbus Communication Module
Page 44 of 159
ProSoft Technology, Inc.
July 24, 2008
Notice the count is now set to a value of 7. The reason for this is that because
the slave device utilizes only 7 Modbus addresses, a count of 7 will cause the
slave to respond with 14 registers (28 bytes) of information. This command will
still occupy 14 register within the MCM.DATA.ReadData array, so make sure
when you setup you IntAddress field for other Modbus Master commands, you
make sure that the addresses 1000 to 1013 are not used for any other
commands.
The COP statement for this type of data is the same as shown in Read Multiple
Floating Point Registers (page 41).
4.4.5 Write to Enron/Daniel Floats
Issuing a Write command to Enron/Daniel Floats requires the use of the Float
Flag and Float Start parameters within the configuration file.
This table provides the addresses that will be written to by the module.
Address Data
Type
Parameter
47001
32 bit REAL
Demand
47002
32 bit REAL
Reactive Power
47003
32 bit REAL
Apparent Power
47004
32 bit REAL
Power Factor
47005
32 bit REAL
Voltage: Line to Line
47006
32 bit REAL
Voltage: Line to Neutral
47007
32 bit REAL
Current
The Float Start and Float Flag parameters must be configured as shown.
The Float Flag alerts the module that it must look at the FloatStart parameter to
know what DevAddress requires double the number of bytes to be issued on a
write command.
1
With the above configuration, any DevAddress > 7000 is known to be floating
point data. Therefore a count of 1 will send 4 bytes of data, instead of the
normal 2 bytes of data to a non Enron/Daniel floating point register.
2
First, Copy the floating point data from the ControlLogix processor into the
MCM.DATA.WriteData array used by the MVI56-MCM module. Below is an
example.