Baldor VS1MX - Appendix E RS485;MODBUS Protocol

RS485/MODBUS Protocol E-1MN762
Appendix E
RS485/MODBUS Protocol
E.1 Introduction
The VS1MX AC Drive is supplied with imbedded RS-485 communications that supports the Modbus-R TU protocol. This
allows the user to set up a multi-drop communications network between multiple VS1MX drives and a PLC or host computer
without the requirement of option boards for the drives. This is a master-slave architecture where the master (e.g. PLC) can
monitor and control multiple VS1MX drives on the same network with other Modbus-RTU slaves. This appendix denes the
specics needed to set up a VS1MX on an RS-485 network running the Modbus-R TU protocol and documents the function
codes and exception codes supported by the VS1MX. For a complete denition of the Modbus-RTU protocol and the
content of specic messages see www.modbus.org.
Figure E-1 Communications Connection for RS-485
Model VS1-CommUSB
USB to RS-485 Converter Kit
RDA(-)
TDB(+)
RDB(+)
TDA(-)
GND
1 2 3 4
RS-485
Echo OFF
2 Wire
2 Wire
RS-422
Echo ON
4 Wire
4 Wire
Switch Sengs
(Rear of Adapter)
RS485-/Modbus – Pin 7
RS485+/Modbus - Pin 8
RS485 Modbus Ground
8
8
7
3
RS485-/Modbus N
RS485+/Modbus P
8
Communicaons Connecon for RS-485
Communicaons
From a VS1-COMMUSB to a VS1MX
or MX RJ
-45 Port
MXST bus connections
RS485-/Modbus – Pin 3