Modbus Network Communications; Introduction - Omron MX2 User Manual

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Introduction

ModBus Network Communications

MX2 Series inverters have built-in RS-485 serial communications, featuring
the ModBus RTU protocol. The inverters can connect directly to existing fac-
tory networks or work with new networked applications, without any extra
interface equipment. The specifications are in the following table.
I
Item
Transmission speed
Communication mode
Character code
LSB placement
Electrical interface
Data bits
Parity
Stop bits
Startup convention
Wait time for response
Connections
Connector
Error check
Cable length
The network diagram below shows a series of inverters communicating with a
host computer. Each inverter must have a unique address, from 1 to 32, on
the network. In a typical application, a host computer or controller is the mas-
ter and each of the inverter(s) or other devices is a slave.
Specifications
2400/4800/9600/19.2 k/38.4 k/
57.6 k/76.8 k/115.2 k bps
Asynchronous
Binary
Transmits LSB first
RS-485 differential transceiver ✕
8-bit (ModBus RTU mode)
None/even/odd
1 or 2 bits
One-way start from host
device
0 to 1000 msec.
Station address numbers from
1 to 247
Terminal connector
Overrun, Framing block check
code, CRC-16, or horizontal
parity
500m maximum
1 2
Appendix B
User-selectable
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