As you may have learned in previous lessons,
automation often requires communication between
heterogeneous systems from different manufacturers.
Each manufacturer offers a proprietary or an open form of a communication protocol.
It is the responsibility of the Automation Engineer or Technician
to configure devices and develop program logic to communicate between systems.
We have created a series of lessons discussing the steps to configure
and program communication between a Rockwell ControlLogix PLC and a Siemens VFD.
So stay tuned for the sequence to this lesson.
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In this lesson, we will discuss how a Rockwell Automation ControlLogix 5000 PLC
using ControlNet network media and CIP protocol
will overall communicate with a Siemens Robicon VFD using Profibus protocol.
However, these two systems will need a device
to help translate the two heterogeneous protocols;
this device is called a “proxy” or “gateway”.
In our example, we will use the Anybus X-gateway AB7803 “PROFIBUS Master”
to “ControlNet Adapter” gateway from HMS.
Part 1 of this lesson, will address the configuration of the ControlLogix 5000 PAC
to the HMS Anybus gateway.
Part 2 of this lesson will address the HMS Anybus PROFIBUS Master configuration
and Part 3, will address the Siemens Robicon PROFIBUS slave configuration.
First, let’s review the overall communication configuration
we will perform to allow communication between the “ControlLogix PLC”
and “Siemens Robicon VFD” using the “HMS Gateway” used in our example.
The ControlLogix PLC will be controlling a pump with a simple ON/OFF command
and its velocity by setting a speed set-point to the VFD.
In response, the Siemens VFD will return the actual speed reference
and VFD status information controlling the pump.
This exchange of control data
and status information is all performed by the HMS gateway.
The HMS Gateway also performs an important responsibility
as “PROFIBUS Master”, controlling the Pump VFD.
We have specific addressing for each side of our network;
On the left-hand side of the network, the ‘CIP network’,
the ‘ControlNet Master’ or ‘Scanner’ will be addressed as ‘Node 1’
and the ‘HMS Gateway’ will be addressed as ‘Node 3’.
On the right-hand side of the network,
the ‘HMS Gateway’ will be the ‘Profibus Master’
and will have the address of ‘1’ .
and the ‘Robicon VFD’ will have the ‘Slave address’ as ‘3’
Please note, when beginning a communication project,
it is best to look at the big picture
and create a spreadsheet with all the tags and data types
to be configured at each system
And we want to point out that the HMS Anybus gateway is not pass-thru
but instead acts as a “translator” using an internal shared common database.
The communication is asynchronous, in that,
the gateway serves two different communication loops,
one for the ControlLogix 5000 ControlNet
and one for the Siemens Robicon PROFIBUS
and the data is shared using an internal Dual Port RAM to the HMS gateway.
Ok, let’s get started with the ControlLogix ControlNet communication
to the HMS gateway.
We will configure the ControlLogix IO configuration first.
We are assuming that the user is
familiar with the basics of Studio 5000 programming software.
Now, I’ll launch the studio 5000 and create a new project.
Next, I’ll select 1756-L71 processor, name the project as “Pump”,
hit "Next" and then hit “Finish” as well.
Next thing that I need to do here,
under the “I/O configuration” folder,
I right click on the 1756 Backplane, and select new Module.
Then I’ll Locate the “1756-CNB ControlNet Bridge” module and press “create”.
In the next window, I’ll leave the “Major Revision” number as it is and hit OK.
Next, I will name the module as “Pump Control”,and press OK.
For this window, I will keep everything as it is and click OK again.
Next, I need to create a ControlNet communication module.
To do this, under the “I/O configuration” folder,
I’ll right click over 1756-CNB/E Pump Control and select “New Module”.
On the left side of the “Catalog” Tab,
I’ll uncheck the “module type category filters” and select the “communication”.
Then I’ll scroll down a bit until I’ll find the “Generic ControlNet Module”,
and then I’ll press create.
Let’s name this module as “Robicon VFD”, with the Node address of 2.
I will also set up the “Connection Parameters” with “Input Instance” of 100,
“Input Size” of 16, “Output Instance” of 150,
Output Size” of 16 and Configuration Instance of 1.
After everything is done,I’ll click ok.
For this window, I’ll leave everything as it is and click OK again.
After the “ControlNet Generic Module” is created,
Studio 5000 software automatically creates “Input”
and “Output Controller” Tags for the RobiconVFD IO .
From the spreadsheet we will use RobiconVFD:I.Data[2]
as the “VFD status” word and RobiconVFD:I.Data[6]
as the “VFD speed reference”
and Robicon:I.Data[7] as the “Pump Amps” reference.
In the Studio 5000 programming environment
I have created a routine and configured the PLC program logic in there.
In the first rung, rung zero, I have set the logic to move the input data
from the VFD to Studio 5000 controller tags
with alias tag names to easily identify the input data by its VFD origin.
If I scroll down to the next rungs, rungs 1 and 2,
you can see the “ZSW1” input status word-bits.
These bits are used as permissive to indicate the Pump is ON
and or if the Pump is Faulted using the “PumpInFwd”
and “PumpFaulted” tags respectively.
In rung 3, you can see “ControlLogix output VFD control”,
“STW1” word-bits will be forced “True” or “False” based on the VFD requirements.
And the output bits in the “STW1” VFD control word
are moved to the ControlNet relevant word,
RobiconVFD:O.Data[0] and the Speed Setpoint,“N_set_A” tag
is also moved to its ControlNet relevant word,RobiconVFD:O.Data[1] .
At this point, ControlLogix ControlNet module
will “Read” and “Write” the ControlLogix processor data to and from the HMS Gateway
for translation into the PROFIBUS language
to be processed in milliseconds
and communicated to the Siemens VFD for pump control.
As we mentioned earlier,
the HMS gateway provides a kind of translation for Siemens Robicon VFD
and the ControlLogix 5000 systems.
In our example, in Network 1,
HMS Gateway is the ControlNet Slave to the ControlLogix
and Network 2, is the PROFIBUS Master to the Siemens VFD.
Generally, the gateway requires very little effort to get it up and running.
However, since all networks are different,
certain settings may need to be adjusted slightly to fit a particular application.
This is achieved through the Gateway Configuration Interface,
which features a text-based user interface
that can be accessed using standard terminal emulation software
such as the Microsoft Hyper Terminal.
From the physical point of view,
the gateway is using a standard RS232 interface.
Once connected, Start “Hyper Terminal” software
and configure it to the correct physical COM port set up on your Laptop.
After you connected, the Main Menu will be displayed
displaying multiple choices with a corresponding number.
I selected number 4, for the Fieldbus system configuration
and set the I/O data size for each network.
We also instructed the HMS gateway to clear the data
if and when the gateway where to go offline as a safety precaution.
This completes the HMS ControlNet slave configuration setup.
This concludes the video, ControlLogix PLC and Siemens VFD Communication Part 1.
Stay connected with RealPars for Part 2 and Part 3 lessons.
In Part 2, we will discuss how to configure
the HMS Gateway PROFIBUS Master communication to the Siemens Robicon VFD.
I hope you have enjoyed learning what will support you in your upcoming project.
If you would like to get additional training on a similar subject,
please let us know in the comment section.
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