Honeywell UDC2800 Product Manual page 376

Table 12-2: Modbus RTU Function Codes Definitions
Function
Name
Code
01 Read Coil
Status
02 Read Input
Status
03 Read
Holding
Registers
04 Read Input
Registers
06 Preset
Single
Register
08 Loopback
Test
16 (10h) Preset
Multiple
Registers
17 (11h) Report
Device ID
For more information, see "Modbus RTU Function Codes" of 51-52-
25-66 Modbus RTU Serial Communications User Manual, which is
available at Honeywellprocess.com.
Chapter 12 - Standard Modbus Read, Write and Override Parameters
Usage
Read the State of a Digital Output
Read the State of a Digital Input
Read Data in 16 bit Register Format (high/low). Used to read
integer or floating point process data. Registers are
consecutive and are imaged from the instrument to the host.
Write Data in 16-bit Integer Format (high/low) ONLY.
Used for diagnostic testing of the communications port.
Write Data in 16-bit Format (high/low). Used to write integer
and floating point override data. Registers are consecutive
and are imaged from the host to the instrument.
Note: UDC will write floating point data using this Function
Code.
Read instrument ID and connection information, ROM
version, etc.
376