NI HW and SW to interact with PLC's?

[Gops]

Hello All,

Does Labview provide options to interact with PLC through buses like modbus, profibus etc., ? what is lookout software? Is it a part of any NI toolkit?

Does NI have hardware for these PLC based buses?

Regards

Gopal

[Bassett_Hound]

Hi Gopal,

There are many options for you to use LabVIEW to connect to your PLCs.  Check the link below for some good reasons to use LabVIEW.

10 Reasons to Add LabVIEW to Your PLC
http://zone.ni.com/devzone/conceptd.nsf/webmain/3c1e0ec203d332bf8625719a0059d8b7

The are really three methods to available in LabVIEW to communicate to any PLC:
a. Digital I/O
b. Industrial Communications (Modbus, plug-in boards, gateways)
c. OPC (OLE for Process Control)

Digital I/O
Using Digital I/O is the simplest form of communication with a PLC.  It consists of passing binary values to and from the PLC using the Digital lines of any National Instrument DAQ or Digital Board.

Check out this this related to using Digital I/O) for Industrial Applications:
NI Digital I/O for Industrial Applications
http://zone.ni.com/devzone/conceptd.nsf/webmain/4F66111C8A95645F86256DF1005C940A

Industrial Communications
Different PLC manufacturers can have different protocols or language for communicating with PLC.  For example, Allen-Bradley (Rockwell) PLCs talk DF1, Data Highway 485 (DH485), Data Highway (DH), Data Highway + (DH+), Remote I/O (RIO), Devicenet, Controlnet,  while  Modicon PLCs speak Modbus, Modbus Plus, and Modbus TCP/IP (Modbus over Ethernet). Whereas Siemens PLCs work mainly with the Profibus protocol.  The most common "standard" protocols seen are DF1, Modbus, and Profibus. The benefit of these protocols is that it translates proprietary PLC communications standards to a more universal standard.

National Instruments offers a variety of reliable and easy-to-use hardware and software tools to help you meet any of your communication needs including Modbus TCP/Serial, DeviceNet, Profibus, Ethernet, CAN, and FOUNDATION Fieldbus.

Check out this link regarding the Commuincation Buses and Protocols available from NI:
Communication Buses and Protocols
http://www.ni.com/comm/

OPC
OPC is Object linking and embedding for process control (whew). The National Instruments LabVIEW Datalogging and Supervisory Control (DSC) Module is the best way to interactively develop your distributed monitoring and control system. The built in OPC client provided by the LabVIEW DSC allows for direct integration of PLC registers and also provides extended functionality to LabVIEW such as configuration-based logging, alarming, scaling, security, and more.  Through the use of Shared Variables, data from PLCs can be shared and transferred seamlessly throughout your network to other computers and devices like the National Instruments CompactRIO Programmable Automation Controller.  The NI LabVIEW DSC Module extends your LabVIEW application to easily develop a high-channel-count data-logging and alarming application without any programming.

Check out these links regarding the DSC Module and PACs:
What Is the LabVIEW Datalogging and Supervisory Control Module?
http://ni.com/labview/labviewdsc/what_is.htm

Programmable Automation Controllers (PACs)
http://www.ni.com/pac/

Lookout is also a software package provided by NI that has drivers capable of doing all three of these communication methods.  Check out the Link below for more information on Lookout.    http://digital.ni.com/manuals.nsf/websearch/3D2A2AB4D33B681186256F0400607461

Sorry for the long post.  Hope that helps a little.

Regards,

Steven Bassett

Message Edited by Bassett Hound on 09-09-2006 01:47 PM

[Gops]

Hello Mr.Bassett,

Your post was very informative. I would like to ask you some more questions regarding the Industrial communications.

From the link you had suggested for industrial communication I can only see the driver support for Modbus. It specifies that we can connect to other devices through a gateway. Can you please give me more details about this gateway.

Further does lookout provide drivers all standard communication protocols like DF1, modbus and profibus.

Can I assume that lookout standalone would be compared with Labview + DSC ?

Regard

Gopal

[Doug M]

Hi Gopal,

Because Modbus operates over either a serial port or an Ethernet port, all that is needed is a driver to communicate using the Modbus protocol.  With the other standards, specialized hardware is required.  National Instruments devices for protocols such as DeviceNet or CAN also include the software driver support.  I didn't see where a gateway was mentioned, but generally a gateway will include a driver to expose the devices as individual communication ports to the host PC.

Lookout is a completely different programming environment than Lookout, but the purpose of both Lookout and LabVIEW + DSC is to create a SCADA/HMI for an industrial control/monitoring application.  Lookout is simpler to program, using a basic object oriented API, while LabVIEW+DSC includes all the powerful programming features that LabVIEW offers.  This link shows all supported drivers that Lookout includes.  If a driver for a specific PLC is not listed, it has no native driver in Lookout, but if you can obtain a 3rd party OPC server for the PLC, Lookout can connect to it as an OPC Client.