Rockwell Automation 900 Temperature Controller Communications Functions - Series B - Manual (Page 9)

1-1 Publication 900-UM004D-EN-E - July 2010
Chapter
1
About Communications Methods
Introduction This chapter briefly describes the supported communications methods and
how to wire equipment. First-time users must read this chapter to ensure
proper installation of the equipment.
The programs for the communications functions are created on the host
device (PLC or computer), and the 900-TCx's parameters are monitored or set
from the host PLC or computer. Therefore, the description provided here is
from the viewpoint of the host device.
All Bulletin 900 Temperature Controllers offer an ASCII communications
protocol format based on CompoWay/F for general serial communications.
This format uses a standard frame format. Therefore, it can simplify
communications between 900-TCx components and the host device.
The 900-TC8, 900-TC16, and 900-TC32 controllers also have Modbus®
communication protocol. Modbus is a standard communications control
method that conforms to the Modicon Company’s RTU-mode Modbus
protocol (PI-MBUS-300 Revision J). It supports functions equivalent to the
CompoWay/F Read Variable Area, Write Variable Area, Operation Command,
and Echoback Test functions.
Simplified communications can include:
• Reading/writing of parameters
• Operation instructions
• Selection of setup levels
Communications are subject to the following condition:
• Parameters can be written only when the Communications writing
parameter is set to ON (enabled).
Modbus is a registered trademark of Schneider Electric