OMRON Inverter 3G3MX2 Modbus communication

Hello gentlemen,

Another day another drive

I have an OMRON inverter 3G3MX2 which I put in to replace a damaged one both of which are identical. In the panel there are a total of 14 of the same inverter but two different sizes. The inverters are connected to an OMRON CP1L via Modbus. The Modbus is used for frequency reference and a separate enable command goes to each inverter terminal.

The one I put in would not has the same unique address as its predecessor but for some reason it does not accept the frequency reference and maintains a zero frequency. When an enable command is sent, the run LED light up but the frequency remains zero. Here's what I found interesting, if I interchange the communication address (C072) between any two iverters both work fantastic and reference the proper frequency set for each one but if I put the addresses back the way they're suppose to be then that specific (new) one goes back to behaving the way I described above.

All help is, as always, very much appreciated.


Kal

http://industrial.omron.com.br/uploads/arquivos/Manual_MX2.pdf

Have you verified the termination resistor on the drive?
Have you spoke Omron on this problem?
It does not make sense that when the address numbers are swapped, everything works correctly. This means that the program is correct. The only other thing would be if the address was 1. These drives can also be a master.

Interesting problem.

gclshortt said:

http://industrial.omron.com.br/uploads/arquivos/Manual_MX2.pdf

Have you verified the termination resistor on the drive?
Have you spoke Omron on this problem?
It does not make sense that when the address numbers are swapped, everything works correctly. This means that the program is correct. The only other thing would be if the address was 1. These drives can also be a master.

Interesting problem.

Click to expand...

Thanks Garry,
I resolved the issue late last night. The issue turned out that they selected Free V/F control method (A044) algorithm and "The inverter regard the value of free-setting V/F frequency 7 (b112) as the maximum frequency" which was set at default value of zero. Now why it worked when I switch communication address is beyond me.

More interesting stuff, the primary problem I had was that CX-Drive couldn't connect with the drive or the few I tried until I tried the first one and then it connected and from there I compared and matched the parameters expect for the address of course. Then I plugged into the old drive which I could still power up and changed the communication address to 1 and bingo I was connected. It now appears that CX-Drive connects only to drives with address 1 . I will confirm later today as I have a few to upload parameters from.


Cheers
Kal

Confirmed. To connect to drive parameter C072 must be 1 and it was changed from a different address to 1 a power cycle has to be performed after the change.

Thanks for the update Kal.