I am new to industry. I have to make a process monitoring system. I have to select sensors and meters and make a process monitoring system. I can select meters matching to physical requirements but I have no idea of making a network out of them.

Most of flow meters communicate through hart protocol. So I could find a hart multiplexer to connect those flow meters together. Is there any hart to ethernet multiplexer (multiple hart devices connects to pc through ethernet protocol). Multiple electricity meters which are operating on modbus rtu have to be connected to a pc through ethernet interface.

Please look at following diagram
http://www.freeimagehosting.net/image.php?873fc1dc65.jpg

That is the one I am thinking of. I need your suggestions and ideas to do that work correctly and easily. Actually I have no idea about the products I have to use for this project. Please help me....

 

Nilupul,

The diagram that you posted is helpful. For the water and steam flow meters in your diagram, my company manufactures the 'EtherMeter', a device that may help you achieve your goal.

It converts flow-rate and totalization from many flow meters (in your case, water and steam) into the Modbus/RTU and/or Modbus/TCP protocols.

Also, if your SCADA system is based on Rockwell controllers, then it will work with DF1 and EtherNet/IP protocols, as well.

If I can help further, you can reach me via my contact page...

http://scadametrics.com/contact/contact.htm

-Jim.

 

Do you need more data from each field device (steam/water) than the primary variable? If not, why do HART?

When I looked at HART multiplexors a couple years ago, it appeared
- that the vendors were not particularly astute on the topic, it was in their catalogs, but it was difficult to find anyone knew

anything about HART MUX's. I couldn't find an actual user of a HART mux or get a referral to a user from MUX vendor.
- the intended software seemed to be asset management software, like Emerson's AMS or Siemens' PDM.
- a HART foundation server was supposed to be used to get data via OPC.

The MUX hardware was about $6k USD then. And I wasn't overly confident about support for the architecture. I'm sure it works, but I was just more comfortable with Modbus. The data needed was primary PV's, no secondaries or diagnostics.

So, I sent the instrument 4-20mA signals into I/O that could handle conversion to Modbus, knowing that SCADA or HMI software can handle Modbus or OPC.

I used Acromag I/O (what you call an analog to Modbus RTU converter) on one job, with Wonderware software.

I used a Honeywell paperless recorder with a Modbus TCP port on another job, because of the need for local trending. The customer used a PC browser to view the recorder screen over a network connection, and they used the Honeywell software for historical trending. Both were somewhere on the order of 30-45 field points.

For your Modbus RTU to ethernet MUX, look at vendors like Lantronix or Digi for Modbus serial server boxes. Make sure you get one that has the Modbus firmware driver.

 

Have you considered using OPC for this? OPC provides you with access to data from your Modbus RTU.... here is some tutorials that will bring you up to speed: http://is.gd/f0XVk

And here is a list of products to build your architecture: http://is.gd/f0Y6r

Hope this is helpful

Wassim Daoud
Global Solutions Architect

 

Thank you bud, This will be much more helpful to me.

 

Bridging across the HART (or Foundation fieldbus) communication is a good idea. It allows you to take advantage of features like meter verification and diagnostics found in magnetic flowmeters and Coriolis mass flowmeters, and to some extent in vortex flowmeters.

See these articles:
http://www.eddl.org/SiteCollectionDocuments/Articles/pg42-47-1-MAG3.pdf

http://www.ceasiamag.com/article-5644-timeforcalibration-LogisticsAsia.html

This site gives some other clues as to why digital communication is useful
http://www.eddl.org/DeviceManagement/Pages/default.aspx

The two articles above mention an alternative to multiplexers: WirelessHART adapters mounted on the transmitter and forming a mesh network up to a gateway to Ethernet.

Cheers,
Jonas