Modbus RTU comm between Koyo PLC and Allen bradley HMI

Hi all ! I can't figure out how to setup the modbus RTU comm. to connect a Koyo DL250-1 CPU with a Panelview Plus 600 from Allen-Bradley.

I use RS-232 communication. I followed the AB procedure on the HMI side and the Koyo procedure on the PLC side. But I don't know what I did wrong. I also need information for the bits and registers. I can't figure out how this works.

Thanks in advance !

Well, you don't give us a lot to work with. More detail that include the exact link to procedures you referred to that at least answering the following.

- What cable and connector did you use
- Did you config kepware modbus driver?
- Did you have success trouble-shooting from either side with a modbus simulator on your computer?

eta: do you mean DL205?

Thank you for your reply !

Yes I use a DL205-1 CPU.

I use a cable with db15 at one end and db9 at the other hand. On db15 side, I use 2 for tx, 3 for rx, 7 for 0V and i jumpered CTS and Rts together. On db9 side, I use 2 for rx, 3 for tx, and 5 for 0V.

I installed the modbus driver into the runtime for the panelview but I am not sure if I did it right as I have no idea how the inputs and output register works (40001,30001, and stuff ...)

I tried many documents from automation direct and also allen-bradley to help me understand how this works but no luck.

On the PLC side (Koyo), I tried something but it doesn't seems to work either...

I think I must start over with some help !

Thanks !

Well, it's quite a project if this is your first time doing modbus. Realistically I would get someone local through this.

You have to do it step by step when you have so many unknowns.

• You have to know how serial communication works and how to wire RS232 and then how to measure or test that it is correct.
• Next you need to hook up a PC as modbus slave so you can test your modbus master (HMI).
• Then you need hook up the PC as a modbus master to test your slave (PLC).
• Then you can hook up both together.

There are some potential differences when it comes to modbus addressing. Best is to go to the modbus organization and read their documents. You need to understand the modbus protocol if you have differences in implementation between master and slave.

You might have to hook up the PC to read what the slave or master is sending out / replying to troubleshoot.

The most common scenario when you hook something up, like you just did, is that is doesn't work. That's completely normal.
To get it to work the electrical part has to be right and the software configuration / programming and addressing on both PLC and HMI has to be correct as well.

PS. If you don't have a scope you might want something an RS-232 tester like this the one below to test the signals.
http://www.bb-elec.com/Products/Ser...l-Data-Tools-Adapters/RS-232-Mini-Tester.aspx

Do you need to load the KEP driver to talk Modbus? Link.

Yes, he need KEP modbus driver. However, even before he gets to that point, the data need to be in the right location at the PLC to be polled, as well as correct port configuration.

I would follow Pete's step which nicely summarize what I would do in OP's shoes.. From OP's question, he is not even sure if the data are in the right registers in the PLC. I have a lot of experience talking people through steps like this on the phone but I figure this would take all day on the phone thus why I suggest OP get local help.

It's not impossible to fight through this on your own, especially to someone who is motivated and got the time. There are some excellent modbus video on the net.

I followed the Allen Bradley procedure but when I am about to test my tags on OPC Quick Client. The value is at Unknown and the signal is Bad. Plus, I can't make my HMI the master according to the technical sheet of the Panelview plus 600.

Do I have to hook up the PLC to the OPC Quick Client first ?

I don't know where to start and which adress to put in my tags. (I tried 000001 and 1000001 (test Input and test output, I think)

Thanks for any help !