Allen-Bradley ControlLogix User Manual

1756-6.5.3 - December 1999
1-2 ControlNet Communication Basics
Module Features
The 1756-CNB module performs two primary tasks:
1. control of I/O data in conjunction with a Logix5550 controller
(scheduled data)
2. support of messaging data for configuration and programming
information (unscheduled data)
The 1756-CNB module has these primary features:
• support for a maximum of 64 bidirectional connections with other
ControlNet devices
• support of up to 20 buffers for unconnected messages
• bridging of unscheduled data (messaging and programming information)
• control of scheduled I/O and scheduled data (in conjunction with a
Logix5550 controller)
Support for up to 64 Bidirectional Connections
A connection is an open communication path between the data producer and
the data consumer on the network. The connection includes information
about the location of the consumer that significantly decreases the data
overhead. By contrast, an unconnected message is a traditional message that
uses the network address of the target device and the data address within the
target.
The 1756-CNB module supports a maximum of 64 bidirectional
connections. These connections can be any mix of unscheduled and
scheduled connections. If your application requires more connections, you
can place additional 1756-CNB modules in the same chassis and on the
same network as the first module to provide additional connections.
Important:The number of connections that can actually be supported on a
network is dependent upon the network configuration. For
example, only 10 to 12 connections can be supported at an RPI
(requested packet interval) of 5ms, and only 4 at an RPI of 2ms.
Important:If you choose to use additional modules to provide additional
connections, be sure to partition your application so that it best
uses the additional modules. See page 11-17 for an example
network.

Allen-Bradley ControlLogix Specifications

General

Communication	EtherNet/IP, ControlNet, DeviceNet, DH+
I/O Capacity	Up to 128, 000 I/O points (varies by configuration)
Redundancy	Supported (with specific modules)
Programming Software	Rockwell Automation Studio 5000 Logix Designer
Operating Temperature	0°C to 60°C (32°F to 140°F)
Programming Languages	Ladder Logic, Function Block Diagram, Structured Text, Sequential Function Chart
Modularity	Yes
Certifications	UL, CE
Processor Type	Multiple options available, including standard, safety, and extreme environment processors
Power Supply	Multiple options available, including standard and redundant power supplies with various voltage ranges (e.g., 24V DC, 120/240V AC)

Summary

Chapter 1: ControlNet Communication Basics

Communication Models and Protocols

Chapter 2: Installing the ControlNet Network

Installing and Configuring Interface Card

Installing ControlLogix and PLC-5C Modules

Connecting the ControlNet Network

Chapter 3: Logix5550 to Logix5550 Unscheduled Messaging

Chapter 4: Logix5550 to Logix5550 Scheduled Communication

Producer and Consumer Application Setup

Network Configuration and Communication Testing

Covers scheduling the network, verifying properties, and testing communication.

Chapter 5: Logix5550 Controller to PLC-5C Unscheduled Messaging

Chapter 6: Logix5550 Controller to PLC-5C Scheduled Communications

Producer Application Setup and Network Scheduling

PLC-5C Configuration and Communication Testing

Details configuring the PLC-5C to receive data and testing the communication.

Chapter 7: PLC-5C to Logix5550 Controller Unscheduled Messaging

Example Setup and PLC-5C Program Creation

Program Download and Message Verification

Chapter 8: PLC-5C to Logix5550 Controller Scheduled Communications

Network and Controller Configuration

Guides configuring the ControlNet network, PLC-5C, and Logix5550 consumer.

Producer Setup and Network Scheduling

Details creating the PLC-5C producer application and scheduling the network.

Communication Verification

Chapter 9: PLC-5C to PLC-5C Unscheduled Messaging Over Two ControlNet Networks

Example Setup and Program Creation

Guides system setup, application creation, and ladder program development.

Program Download and Communication Testing

Details downloading the program and testing the message bridging.

Chapter 10: Controlling I/O Over a ControlNet Network

I/O Configuration and Setup

Guides adding local and remote CNB modules and I/O modules to the configuration.

Ladder Logic, Download, and Network Scheduling

Details editing tags, creating ladder logic, downloading, and scheduling the network.

Testing Remote I/O Operation

Chapter 11: Adding an I/O Chassis to an Existing ControlNet Network

Network Expansion Configuration

Guides adding a second remote CNB module and analog I/O to the network.

Logic, Download, and Network Scheduling

Details editing tags, modifying logic, downloading, and scheduling the expanded network.

Testing Analog Output Operation

Chapter 12: Troubleshooting

Module Status Indicators and Causes

ControlNet Network Status Indicators

Appendix B: Creating Produced and Consumed Tags

Tag Creation Fundamentals