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Modbus communication

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I'm having a problem with the Jazz.

I want to communicate with a few Omron MX2 inverters jusing Modbus.

In the old situation i use a Omron PLC and this works ok.

Now we want to convert our machines into Unitronics powered machines.

I want to send the position,start/stop,frequention,and counter clear to the inverter.

We make some simple position tasks with this inverter so there is a encoder directly to the inverter.

So it is possible to send a position to the inverter with modbus and the inverter calculate the position.

Now a cant get any connection between the Jazz and the inverter.

I use the rs485 com port for the connection between the inverter and plc.

Here are the parameters from the Omron plc:

This is to send the frequenty to the inverter.

move/store: node nr. #1

move/store: function code #10

move/store: number of bytes &7

Move/store : register #1

move/store : aantal registers #1

Move/store : number of bytes+data #0200

tranfer bit : #808 control word

frequenty 500 dec. uint

tranfer bit : #808 control word

frequenty 500dec. uint

Here you can download the user manual for the inverter.


Page 303 are the modbus registers.

Also a problem the registers are in Hex and i cant fill in hex numbers into the Jazz.

I hope you can help me,its the last Omron machine we built so we want to go Unitronics.

Regards Leon

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Hi Leon,

Im sorry but you did not give enough information to give you an actual answer, however I can give some things to look at.

You said you have a JAZZ are you using the "JZ-RS4" com port kit"

You have to make sure you set up for the required node ID, com speed Ect.. see the help files on Modbus.

As far as the HEX indications in you Omron manual. Hex is decimal and decimal is hex You just have to use the corect decimal value to equal the hex value you need. For example lets say you wanted to write a max frequency to Omron data location 124Fh (on page 312 of your Omron manual) is 4687 in decimal (use your windows scientific view of the built in calculator to make the conversions if you need to)

So if you needed to write this you would use lets say Omron function code 10h = decimal function code 16. I have never used a JAZZ for communications so I am assuming that it will allow a code 16 write like the vision controllers. but assuming it does, you would use a function code 16 write to location 4687 and if you wrote a decimal value of 6000 to this location you would be setting the max frequency value to 60.00.

Sorry I can't be of more help but if you are not talking at all, follow the help files and get the com speeds, parity, stop bits, node number, and packet size to match before any communication will be possible (asuming the physical wiring between the two is correct)


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