Quantum 140 NOE771 00/01 Communications with Dual Port Client Device

[AP7311]

Hi,

First of all, thanks in advance for those who support and advises.

I have a Modbus/TCP operational network as shown below.

However, at any 1 time only 1 LAN is able to communicate instead of both LAN networks of the device. In another system with S.E Premium Unity PLC, both LAN networks are able to communicate at the same time.

Thus, I would like to enquire if this is a limitation of Quantum NOE 771 whereby only 1 LAN can communicate at any one time or whether I have missed out any parameter/configuration settings? Any issue on the IP address configurations?

Please advise.

Thank you very much for the advise and assistance.

[Robert_Willis]

Based on your configuration I suspect it has to do with the Client. What is the client and how is it configured to handle the redundant LAN connection to the Modicon Quantum Hot-Standby System. Based on your comments, it appears that it will only communicate on the the "Primary" connection until a failure occurs.. To test this theory establish communication from the Client to the Modicon Quantum 140NOE771 module, disconnect the Ethernet Cable and confirm that communication is now established to the alternate 140NOE711 module.

[AP7311]

Hi Robert,

First of all, thanks for the response, sincerely appreciated.

What you have mentioned has been proven correct in this case.

However, we can't conclude that the issue is due to the client device as the same device is used with Premium Unity PLC NOE to be able to communicate with both LAN network at the same time.

There are 2 possibility which I suspect:

1. Due to common IP domain with aaa.aaa.aa  same addressing, not sure how much this will affect the communications;

2. Communications is through read/write logic (polling) instead of using the IO scanning functions

Are there any more conclusive causes?

What do you think? 

Thanks!