Beijer Electronics AN-BEI-H2-038 User Manual
Bfi applications support library
APPLICATION NOTE AN‐BEI‐H2‐038
Date: 15/02/12
AN‐BEI‐H2‐038 Modbus RTU Control and Register Mapping
1
BFI Applications Support Library
Application Note AN‐BEI‐P2‐038
Title
Modbus RTU Control and Register Mapping
Related Products Beijer Frequency Inverter H2
Level
3
1 – Fundamental ‐ No previous experience necessary
2 – Basic – Some Basic drives knowledge recommended
3 – Advanced – Some Basic drives knowledge required
4 – Expert – Good experience in topic of subject matter recommended
Overview:
This document provides information on the Modbus RTU memory mapping that is implemented in the Beijer Frequency Inverter
H2 drives, detailing which addresses are used to read and write data to / from the Beijer Frequency Inverter H2 in a Modbus RTU
network. All data registers within the drive are Holding Registers, and can be accessed by means of the Modbus commands 03
Read Multiple Holding Registers and 06 Write Single Register only.
The Modbus Request PDU specifies the starting register address and the number of registers. In this case, with some Modbus
Master Systems, it may be necessary to subtract 1 from the register number (e.g. some systems treat holding register 1 as
address 0).
The Manufacturer adopts a policy of continuous improvement and whilst every effort has been made to provide accurate and up
to date information, the information contained in this document should be used for guidance purposes only and does not form
the part of any contract.
MODBUS RTU Protocol Specification:
The following table highlights the specification for the Modbus RTU implementation.
Protocol
Modbus RTU
Error check
CRC
Baud rate
Parameter Selectable as follows :‐
9600bps, 19200bps, 38400bps, 57600bps, 115200bps (default)
Data format
Parameter Selectable as follows :
1 start bit, 8 data bits, 1 stop bits, no parity. (default)
1 start bit, 8 data bits, 2 stop bits, no parity.
1 start bit, 8 data bits, 1 stop bits, even parity.
1 start bit, 8 data bits, 1 stop bits, odd parity.
Physical signal
RS 485 (2‐wire)