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Introduction
Overview
Revision 4 HC900 Hybrid Controller Communications User Guide 1
9/03
1. Introduction
1.1 Overview
The HC900 controller provides Modbus communication support on three communication interfaces.
• Network port: Modbus TCP on an Ethernet connection
• RS232 port: Modbus RTU
• RS485 port: Modbus RTU
The user may find it convenient to print out the Modbus addresses for various parameters of the
configuration (signal tags, PID loops, SP programmer, etc.) using the HC Designer report functions. With
HC Designer Ver. 2.1 and later, these reports may also be exported to .csv files for view/manipulation in a
spreadsheet and possible import to other HMI applications.
1.2 Modbus/TCP Interface
Introduction
HC900 controllers support the Modbus/TCP (also called Modbus TCP/IP or Modbus Ethernet) protocol for
communications with third party HMI and SCADA software via a direct Ethernet TCP/IP connection.
The controller’s Ethernet 10Base-T Host port is used for the Modbus/TCP connection. Ethernet TCP
allows multiple concurrent connections to hosts for data interchange. The HC900 supports 5 concurrent
host connections using Modbus/TCP protocol messaging via this port.
Interface Preparation
ATTENTION
To access the controller you must have a current Hybrid Control Designer configuration file available. Some
data is referenced relative to number, such as Signal Tags and Variables.
Other principal blocks, such as PID blocks, have offsets for parameter access dependent on the order in
which the blocks were placed on the Function Block Diagram.
It is strongly recommended that you upload the controller configuration using the Hybrid Control
Designer configuration tool to assure that you have a current configuration.
The Hybrid Control Designer tool provides a series of reports for use in Modbus Address identification.
The "Tag Information" report lists the variables and Signal Tags in numeric order along with their Modbus
Addresses.
A "Block Modbus Address" report lists the starting addresses for all principal blocks configured, identifying
the offset.
Modbus/TCP Protocol
Modbus/TCP protocol, developed by Groupe Schneider’s Modicon Division, is a popular, open standard for data
interchange over Ethernet TCP/IP networks using a Modbus RTU command structure.
It is simply an encapsulation of Modicon’s Modbus RTU protocol within a TCP/IP frame as shown below, which
includes header information and the Modbus frame.