Parker AC30V Series, Product Manual

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A-3
Modbus TCP
AC30V series Variable Speed Drive
FIXED PARAMETER MAPPING - STRINGS
Strings parameters have a parameter number that represents the whole string. This parameter number is mapped to two registers so limits
access to the first four characters. Additional contiguous parameter numbers are set aside so that the whole string can be accessed: one
additional parameter number for each four characters. The strings are packed into the registers
low byte first
.
String Example
A string parameter called My String has a string length of 12 characters (plus the null terminator). This will have one parameter number allocated
for the whole string (in this example 161) and 3 further parameter numbers for the string fragments (162-164).
If the value of the string is “0123456789AB”:
Parameter
Number
Represents Register
Number
Register Value
hi-byte lo-byte
0161 whole string
“0123456789AB”
00849 ‘1’ ‘0’
00850 ‘3’ ‘2’
0162 Fragment
“0123”
00851 ‘1’ ‘0’
00852 ‘3’ ‘2’
0163 fragment
“4567”
00853 ‘5’ ‘4’
00854 ‘7’ ‘6’
0164 fragment
“89AB”
00855 ‘9’ ‘8’
00856 ‘B’ ‘A’
Note: This is example is not a real parameter.
As each AC30V parameter maps to two registers, if the registers that represent the whole string are accessed then only the first four characters
will appear. To access the whole string over Modbus use the registers that map to the parameter number of the whole array plus one, in this
example 0162 (register 00851 ). A multiple read or write of registers will then provide access to the whole string.