Modbus RTU on Compact Logix

[Coulombboy]

Hi Everybody,

I am have power meters with built in RS485 port that talks modbus to be connected to AB compact logix. My problem is I am unsure whether the compact logix can talk directly to the power meters since the indicated serial port on the manual is RS232. I have used micrologix 1100 and the port is a RS-232 and 485 combo.

In case i need a converter, what AB should i use?

Thank in advance

 

[harryting]

You should be able to use any 485/232 converter. Some of the cheap one only cost about $10 off ebay.

I would double check on the compactlogix, open up the project with RSlogix and go to the port setup. Same with meter, it should talk 232 so double check that as well.

 

[JasonSelf]

Prosoft

To talk modbus with either compactlogix or controllogix your best bet is to use a card from Prosoft.

I use the MVI69L-MBS
http://www.prosoft-technology.com/P...al-Lite-Communication-Module-for-CompactLogix

That is the lite version, the extended version has 2 ports and can run more commands.

IMO Prosoft support is second to none and getting these cards up and running couldn't be a whole lot simpler, you configure the device in their software and it generates and add on instruction that you bring into RSLogix5k.

 

[harryting]

Jason is right, I forgot that Compactlogix doesn't do Modbus, AFAIK.

 

[(8{)} ( .)]

You can use you ML as is. It will be much cheaper than buying a ProSoft card. If I remember correctly you have to connect to pins 1 and 8 of the round connector (correct me if I'm wrong) no fun but possible.

Then you have to write a message read instruction to read from your power meter.

Final step is to read the data from the ML1100 into the Compact logix.

Good Luck,

Yosi

 

[JodyM]

I just completed a project talking modbus from two genset generators and two beltscales on a sand system that was run by redundant 1769-L30's. Best bang for the buck I found was using micro820. The gensets were rs485 and the scales modbus/tcp.820 has both ports native, a couple message instructions and project done. biggest learning curve was connected componets workbench, I think rockwell could have done a better job on it.

 

[Jmeadows7676]

You can use the 1769 compact logix for Modbus. There is a very detailed sample project on Rockwell site for this. You need a 232 to 485 converter and of course they recommend their own 1761-Net-AIC, but i have successfully done it with different types of converters. If you have the RSLogix 5000 software you should have the Sample Project. Usually defaulted to location C:\RSLogix 5000\Projects\Samples
Link to Sample download http://search.rockwellautomation.co...&output=xml_no_dtd&proxystylesheet=samplecode

 

[Firejo]

Or you could get one of these. Rockwell does a very poor job of promoting it and it’s pretty hard to find on their web page but I’ve used one before and it’s pretty easy to setup and it works well.
http://www.google.com/url?sa=t&rct=...Zc0C0FgO8aPrFX0cg&sig2=wylCHAPk9GYXPAZBCvetAg

 

[nettogrisen]

+1 for the SM2 module
I've used it on several projects.