Very Low Cost Modbus PLC

[Archie]

I'm investigating the possibility of developing a Modbus driver for the Advanced HMI project, but I do not have any hardware that supports Modbus.

What is the lowest cost PLC I can get that supports both Modbus over RS232 and Modbus/TCP over Ethernet?

I looked at the Automation Direct CLICK, but it does not support Ethernet.

 

[JesperMP]

Hi Archie.

Since you work with Beckhoff already, how about Beckhoff ?
Have you seen that they have announced new lower cost PLCs, CX8000 and CX5000 ?
I doubt that they will come anywhere near the Click PLC pricewise, but my guesstimate for the CX8090 is 400 € / 500 $ which is quite reasonable.
http://www.beckhoff.de/english/embedded_pc/cx8090.htm

 

[ndzied1]

Archie,

There are many Modbus simulators available for PC's. They can be masters or slaves. I think this is the way to go as you will get much more information than using a controller. Obviously, you will want to test on real hardware eventually but to start out a simulator might be easier. Something like Ocean Controls Modbus View comes to mind.

I was just telling someone today that it would be great to have a Modbus/TCP driver for your Advanced HMI system. I have some I/O blocks for using for demo's and they are Modbus/TCP. It would be great to setup an Advanced HMI screen or two for displaying them.

Please keep us posted.

 

[Archie]

Thanks for the suggestions. I'm not sure why I didn't think of a simulator, but I did find one here:

http://sites.google.com/site/plcsimulator/Home


It also has a simulator for DF1 and I tested it with the Advanced HMI.

This simulator will get me started on the Modbus driver.

I'll have to check the Beckhoff hardware to see if they have a controller that supports Modbus over both RS232 and Ethernet.

 

[exabmorgan]

Someone gave me this MFC C version of a modbus simulator a long time ago. The executable and source are included:
http://www.adamforum.com/viewthread.php?tid=1147
(sorry about cross-forum posting, but the zip files are too big for this site)

Also here is a C# modbus class I've seen around:
http://www.nmodbus.com/

 

[vernon1]

Hi Archie, try the new F-series super PLC from Triangle, it talks modbus 232/485 over TCP ethernet. A great piece of kit for about $250. http://www.tri-plc.com/

 

[bkottaras]

I'm investigating the possibility of developing a Modbus driver for the Advanced HMI project, but I do not have any hardware that supports Modbus.

What is the lowest cost PLC I can get that supports both Modbus over RS232 and Modbus/TCP over Ethernet?

I looked at the Automation Direct CLICK, but it does not support Ethernet.

Horner XLe, XLt and Horner XL6 support Modbus.
Add-ON etherent module will get you Modbus TCP.
Prices vary but you cna buy the units that come with no build in I/O which are cheaper.

 

[Joe_WaZoo]

Archie,

You could borrow a Red Lion HMI and set it up as all three options, Modbus RS-232, Modbus RTU via RS-485, and a slave on ModbusTCP. Find out who sells them in your area and see if you can borrow one. Most of guys on the street will have a few to loan customers to try out.

Thanks,
Joe_WaZoo

 

[Mark-]

Hi,

Look at http://www.peakhmi.com/. There is a free slave simulator.

Mark

 

[Archie]

Thanks for the additional recommendations.

I've been using one of the simulators and now have a rough prototype driver working with Advanced HMI. I should be able to post a Beta test version in about a week after I do some clean up on it.

 

[lostcontrol]

Hi Archie,

Did you ever get the Modbus RTU driver developed?

 

[doggo]

Hi Archie,

Did you ever get the Modbus RTU driver developed?

Yes, wondering same thing here. A Modbus RTU interface would open up a slew of low cost plc and process instrumentation that support modbus on older networks.