Modbus Data Types; Modbus Function Codes; Table 3-2: Modbus Function Codes - Honeywell SMV800 User Manual

3.2.4. Modbus data Types

Thetransmitter's mapped addresses store and use data types supported by many
Modbus-compatible PLC's and host controllers.
Please refer the Modbus table
addresses and corresponding function codes.
All registers in this document are referenced to zero. The register in Modbus
messages are referenced to zero. Floating point values are stored as single precision
IEE 754 floating point numbers. These numbers are stored as two 16-bit registers.
Read and Write request for a sinlge parameter is supported, reading and writing of
multiple parameters is not suggested.

3.2.5. Modbus function codes

The SMV800 Modbus device supports the following function codes, which include
read, write and diagnostics commands.
Function
code
01
02
03
04
05
06
16
65
Once the transmitter has been configured, the configuration data can be protected by
removing the write protect jumper. This write protect jumper located on the device. If write
protect jumper is removed and host tries to write to a register location, the Modbus
Exception Illegal Function Code Address (01) will be returned. Any exceptions to this are
noted in the Modbus register maps.
Refer to SMV Transmitter User's manual or Quick Start guide listed in
for location of Write Protect Jumper.
Revision 1.0
Table 3-2

Table 3-2: Modbus Function Codes

Command Description
type
Read Read coil status
Read Read input status
Read Read holding register
Read Read input registers
Write Force single coil
Write Force single holding
register
Write Force multiple holding
register
Read Read file records
SMV800 Modbus User's Guide
for lists of data types per their mapped
Explanation
Read ON/OFF status of one
coil or consecutive coils
Read ON/OFF status of one
discrete input consecutive
discrete input
Read values of one or more
holding registers
Read values of one or more
input registers
Set coil to a specified ON or
OFF state.
Write a value to holding
register
Write values to consecutive
holding registers.
Read file records
References
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