Honeywell UDC2500 Function Code 20 14h Read Configuration Reference Data, Description, Byte Count

Modbus RTU Function Codes

9.3 Function Code 20 (14h) - Read Configuration Reference Data

Description

Function code 20 (14 Hex) is used in this instrument to read information stored in its configuration database. Each configuration item is explicitly addressed by a file number and register address. IEEE 32-bit floating point and 16-bit integer formats are supported.

Request and Response Formats

The Request and Response formats for Function code 20 (14 Hex) are shown below. Details for each block reference follow.

Request Message Format

Slave

Address

Function	Byte	Reference
Code 14	Count	Type

File	Register	Register
Number	Address	Count

Reference

Type

File	Register	Register
Number	Address	Count

CRC Data

CRC Data

Response Message Format

Slave	Function	Byte	Data	Reference	Data	Data	Data
			Byte
Address	Code 14	Count		Type
			Count

Data

Data

Byte

Count

Reference

Type

Data

Data

Data

Data

CRC Data

CRC Data

Byte Count

The Byte Count equals the number of bytes transmitted in either the request or response message and will be the minimum number required to transmit all requested data.

Data Byte Count

The Data Byte Count is the number of data bytes of the sub response including the Reference Type but not including itself. A floating point sub response has four bytes of data and one byte representing the reference type making the data byte count equal to five.

182 UDC2500 Universal Digital Controller Product Manual 4/07