User manual

Modbus RTU
Modbus RTU 1MN744
Modbus Application Layer
MODBUS is an asynchronous serial high-speed binary protocol that supports master/slave communications
between the H2 drive and external devices such as host computers, option cards, man machine interfaces, and
factory bus gateways. This protocol has three layers. The first layer is known as the Physical Layer (PL) and
supports RS485 wiring. The second layer is known as the Data Link Layer (DLL) and supports Remote Terminal
Unit protocol, RTU. The third layer is called the Application Layer (AL). This layer supports the host application
coils, discrete inputs and holding registers.
This document defines the Application Layer (AL) of this protocol as it relates to the H2 control. The MODBUS
connector is P3 which is built into each H2 Control Circuit Board. Refer to Figure 1.
Figure 1 RS485 Connector and Jumper
Fault
USB
USB Port
J1 J2 J3
JP1 JP2
JP3
11
1
RS485
Keypad
Connector
Ribbon
Cable
REGEN
Connector
Control
Circuit
Board
JP6
JP5
P1
J7 J8
P2
P3
SGABS
ENP
EPN
INP
DFT
Factory Settings
as shown
Note factory connection of
J2-8 (Enable) to J3-24.
248
1
JP3
1
No Termination
120 ohm Termination
2-Wire RS485 Connection
Data+
Data-
A
B
S
P3
From
Master
See recommended tightening torques in control manual.
Definitions
H2 drive - Next generation of Industrial drives
RTU - Remote Terminal Unit
PDU - Protocol Data Unit
DLL - Data Link Layer
AL - Application Layer
Master - A network device (host) that initiates communications
Slave - A device (like H2 drive) on the network that responds to a command when requested by a master
H or L - a Modbus Reference followed by an H or L indicates the high or low 16-bit word of a 32-bit
number.
RS 485 Connection and Termination
Refer to Figure 1. Connect the RS485 connections as shown to P3 terminals A and B with shield connection to S.
Set jumper JP3 as desired (termination or no termination).
RS485 Factory Communication Settings
The factory settings for RS485 serial communication set in the Level 1 Communications parameter block as
follows: 19200 Baud, Eight Data Bits, Parity None, 1 Stop Bit, Drive Address 1
Block Title
Parameter P# Adjustable Range Factory
COMMUNICATION
BAUD RATE 1701 0-9600, 1-19200, 2-38400, 3-56000,
4-1 15200
1
PARITY 1702 0-None, 1-Odd, 2-Even 0
STOP BITS 1703 0-One, 1-Two 0
DRIVE ADDRESS 1704 1-247 1
OPTION CARD RESET 1705 0-OFF, 1-ON 0
SECURITY DEFAULT 1706 0-NO, 1-YES 0
Modbus Default Addressing Mode
Only the Zero Based Absolute Addressing Mode is supported at this time. In this method of addressing the actual
reference number listed in the tables below are sent in the protocol itself. For example, to read holding register
40001, the address 40001 is actually sent in the address field of the protocol.