Honeywell UDC3500 - Table 9-3 Register Parameter ID Address Format for Function Code 20

Modbus RTU Function Codes
3/07 UDC3500 Universal Digital Controller Product Manual 341
Reference Type Definitions
The Reference Type definition is always 06.
See examples in Subsection 9.3.1
File Number
The file number word contains the register number from the register address structure
tables on page 339. Although the register address structure tables indicate up to 13 data
registers are available for access, only register address 3 is currently supported.
Register Address
The register address word represents the tag ID number for the parameter(s) being
accessed. The register address word is made up of two bytes. The LSB contains the tag
ID number. The tag ID numbers represent the parameter’s register address(es). See
Section 10 for the tag ID numbers. The MSB contains the control loop and database
extension using codes as shown below:
Modbus register address (High register, Low register)
00 h,xx - loop 1 basic data base registers
01 h,xx - loop 2 basic data base registers
40 h,xx - loop 1 extended data base registers
41 h,xx - loop 2 extended data base registers
xx = Modbus parameter ID register address in hex– Implied Format
Table 9-3 Register Parameter ID Address Format for Function Code 20
Register
Address(es)
(Decimal)
Register
Address(es)
(Hex)
Format
001 to 127 0001 to 007F
analog formatted data
(2 registers – IEEE 32-bit floating point)
128 to 255 0080 to 00FF
integer formatted data
(1 register – 16-bit integer)