12
Memory
Mapping:
Numbering
When accessing a parameter value in the
drive, note the Conversion Index and Data
Type of the parameter. These are shown in
the parameter table in the back of the drive’s
instruction manual.
The conversion index is used to properly scale
the value that is transmitted over the serial
communications. This is necessary because
only integers are passed over the serial
communications. To represent decimal
numbers, a conversion factor is associated
with each conversion index. To convert a value
passed over the serial communications to the
actual value, simply multiply it by the index.
Example: Parameter 201,
Minimum
Frequency
, has a conversion index of -1.
The conversion factor is therefore 0.1. A
value of 150 that is transmitted via serial
communications, therefore, represents
150 x 0.1 = 15.0.
The data
type indicates the number of bits
needed to transmit the number via serial
communications. 8 or 16 bit data occupy one
Modbus RTU register while 32 bit data requires
two registers.
Example: Parameter 515,
Data Read-out:
Power kW
, has a data type of 7. It is a
32-bit unsigned number. In order to read
the output power from the drive, it is
necessary to read two Modbus RTU
registers.
Index
Factor
74
3.6
2
100.0
1
10.0
0
1.0
-1
0.1
-2
0.01
-3
0.001
-4
0.0001
Conversion
Index and
Data Type
Data Type
Description
3
Integer 16
4
Integer 32
5
Unsigned 8
6
Unsigned 16
7
Unsigned 32
9
Text string
Conversion Index
Data Type
A coil or register number is offset by one from
the coil or register address. Coil and register
numbers start at 1 while the coil and register
addresses for them start at 0. Therefore, to
find a coil or register address from the number,
subtract 1.
Summary of Contents for Mobrus RTU TR1 Series
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