Modbus Framing; Address Field; Function Field; Data Field - Veesta World V-PM2000 Series User Manual

VP-2040 Enhanced IED
V-PM2000 Series, Veesta Power Measurement
Instructions & User's Manual
8.4

Modbus Framing

Address
8-Bits
8.4.1

Address Field

8.4.2

Function Field

Code
3 (03H)
5 (05H)
16 (10H)
8.4.3

Data field

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means of checking for errors. No response is transmitted if any error
has occurred.
Modbus Message Format is as bellow:
Function
8-Bits
The address is the beginning of the frame and consists of 8-bits
(1-247). These bits indicate the user assigned address of the slave
device that is to receive the message sent by the attached master.
Each slave must be assigned a unique address and only the
addressed slave will respond to query that contains its address.
When the slave sends a response, the slave address informs the
master which slave is communicating.
The function code field tells the addressed slaves what function to
perform. Table lists the function code, all measuring and action that
initiated.
Table 8-2: VP-2040 Modbus Function Codes
Meaning
Read data
Execute operation
Preset multiple - register
The data field contains information needed by the save to perform
the specific function or contains data collected by the slave response
to query. This information may be values, address references, or
limits. For example, the function code tells the slave to read a
register, and the data field is needed to indicated which register to
Chapter 8 - Protocol and Communication
Data
N * 8-Bits
Action
Obtain current binary value in one or more
registers
Perform specific command operation
Place specific binary value into a series of
consecutive multiple - registers
Check
16-Bits
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