Calculating Connections in an Ethernet/IP System

Doug BrockAutomation Engineer, Chattanooga

doug.brock@kendallelectric.com

What is the biggest consideration when designing your Ethernet/IP

system?

What are the considerations when designing your Ethernet/IP system?

It’s not your only consideration, but one of the biggest is to make sure you pick a processor and Ethernet/IP module that has enough capacity to handle the number of devices you are connecting to the Ethernet/IP network. In order to do that you have to calculate the number of connections your system will use. This presentation covers a manual way and also an easy way to count your connections.

What are the considerations when designing your Ethernet/IP system?

• Limits are set by capacity of Controller and network module

• Two types of connections – CIP and TCP

What are the considerations when designing your Ethernet/IP system?

• Limits are set by capacity of Controller and network module

• Two types of connections – CIP and TCPA processor and a communication module use connections to establish the communication link between the controller and other devices such as local and remote I/O modules, HMIs, drives, etc… Also messages and produced/consumed tags use connections.

• The best place to find a listing of the connection capacity of Logix controllers and network modules is in Rockwell Automation manual 1756-RM094_-EN-P.

(follow this link)

• Search by Publication Manual for 1756-RM094_-EN-P

• Look on page 14 of this manual.

What are the considerations when designing your Ethernet/IP system?

• Limits are set by capacity of Controller and network module

• Two types of connections – CIP and TCP

Generally speaking every IP address is going to use a TCP connection and then it is also going to use one or more CIP connections.

• The best place to find an explanation of what connections are and how they are used is in Rockwell Automation manual ENET-AP001D-EN-P.

(follow this link)

• Search by Publication Manual for ENET-AP001D-EN-P

• Start reading from page 15 of this manual.

Performing the CalculationConnection Type

ExamplesDevice

QuantityX Connections

per Module= Total

Connections

Local Connections Local I/O Module

3 x 1 = 3

Remote Connections Remote Ethernet/IP Comms Module

2 x 1 = 2

Performing the CalculationConnection Type Device

QuantityX Connections

per Module= Total

Connections

Local Connections Example:Local I/O Module

3 x 1 = 3

Remote Connections Remote Ethernet/IP Comms Module

2 x 1 = 2

This table is straight from the publication listed above (1756-RM094_-EN-P) on page 15. Fill out the sheet, multiply out the rows, and add up the last column. There is your total number of connections.

Totaling Connections

So that is the manual way of determining how many connections your system uses. There is a much easier way. Rockwell Automation has a free software package called the Ethernet/IP Capacity Tool that will add up the connections for you. It will also give you an idea of how much overall bandwidth you are using in your system.

Link to the download:

(Ethernet/IP Capacity Tool)

Screen shot of Ethernet/IP Capacity Tool

Screen shot of Ethernet/IP Capacity Tool

The tool is easy to use. Select your processor from the pull-down menu then add the devices that will be on your Ethernet/IP network. Click compute and the software gives you your total connections and other information.

Ethernet/IP Capacity Tool Demo

I posted a simple and short demo of the Ethernet/IP Capacity Tool on YouTube. Here is the link:

http://www.youtube.com/watch?v=DnCaU_GdvpI

That’s the down and dirty of calculating how many connections

your system requires on Ethernet/IP.

More information on Ethernet/IP is available on the Rockwell Automation

website at:

Ethernet/IP Resources