Revision 1.0
SMV800 Modbus User's Guide
Page 107
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
Table 3-2
for lists of data types per their mapped
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.
Table 3-2: Modbus Function Codes
Function
code
Command
type
Description
Explanation
01
Read
Read coil status
Read ON/OFF status of one
coil or consecutive coils
02
Read
Read input status
Read ON/OFF status of one
discrete input consecutive
discrete input
03
Read
Read holding register
Read values of one or more
holding registers
04
Read
Read input registers
Read values of one or more
input registers
05
Write
Force single coil
Set coil to a specified ON or
OFF state.
06
Write
Force single holding
register
Write a value to holding
register
16
Write
Force multiple holding
register
Write values to consecutive
holding registers.
65
Read
Read file records
Read file records
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
References
for location of Write Protect Jumper.
Summary of Contents for SMV800
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