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Fault

Number

Note: 1. All parameters support 485 reading. Refer to parameter code for parameter read-write

address: For example, p 03 -09, read and write addresses are decimal 309

2. Parameter write reference drive permission settings. For example, if the current

permission level of the drive is 1, parameters higher than permission 1 cannot be written. Parameter

writing is not saved when power is off.

10.3 Overview of Modbus Communication Protocol

10.3.1 Introduction

The Nexus Monitor communicates with other devices using the RTU transfer mode of the AEG Modicon

Modbus protocol. This communication applies to both RS-232 and RS-485 standards.

RS-232 communication requires a single connection between a Nexus Monitor and one other device,

using only channel 1 of the Nexus Monitor.

RS-485 supports multiple Nexus monitors connected to a single network and is a two-wire connection

up to 115200 baud with ports 1-4 available.

10.3.2 Communication Package

Communication occurs between a Modbus master and one or more Nexus slaves. The master initiates

all communication by sending a "request packet" to the designated slave, which replies with a "reply

packet". The communication packet consists of a string of 8-bit bytes, as follows:

·Slave address, one byte

·Function code, one byte

·Data, N bytes, high byte first, low byte later

· CRC (RTC Error Detection Code), 2 bytes

·Dead time, 3.5 byte transfer time.

A maximum of 127 registers can be sent in a single communication packet.

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