1756-EN2TR for Remote chassis connections

[rahulkumardave]

Dear Experts,

We are going to have 4 numbers of 1756-A17. Can I use 1756-ENBT in first and last chassis and 1756-EN2TR for daisy chaining for the 2nd and 3rd chassis - If we DO NOT Want to use the Ethernet Switch?

Any idea? Has anybody tried this option already?

Regards,
--Rahul.

 

[rdrast]

What?
Isn't the EN2TR an Ethernet switch?

 

[rahulkumardave]

What?
Isn't the EN2TR an Ethernet switch?

No...!! EN2TR is the slot based module having 2 RJ-45 ports.
See the extract from the RA Manual as attached

Regards,
--Rahul.

 

[Contr_Conn]

The answer to your first question is yes - you can do it, but I would use EN2T instead or ENBT

second statement - to ports on EN2TR are from built-in switch

 

[The Plc Kid]

With just 2 chasis you can just do enbt to enbt correct?

 

[Contr_Conn]

ENBT to ENBT will require crossover cable
EN2T (or EN2TR) has automatic crossover detection and can be connected with standard patch cables

 

[The Plc Kid]

Thanks Contr_Conn

I was just curious as I have always done it with a managed switch stratix or Hirschman.

Any advantage to one method over the other?

Other than reduced cost when not using a switch?

 

[rahulkumardave]

Thanks Contr_Comm.

For The_PLC_Kid: Cost is not the only issue to avoid using Ethernet switch. As the connections between racks should be the PLC internal data exchanges, we want to avoid somebody trying to connect to that network (Usually with the Ethernet switch - people have a tendancy to connect when they want to access to the network). Another thing is we do not want the process to jeopardise due to an external component (Like Ethernet Switch) failure.

Regards,
--Rahul.
P.Eng, TUV FSEng

 

[The Plc Kid]

Makes sense.

Here I acomplish the same thing though as both chasis share a vlan seperate from everthing else. and ethernet cables are locked in place and can't be moved. Space ports are locked/block also.

There is a service port on the inside and outside of the panel plus everyhing is networked together for service.

 

[rdrast]

Thanks Contr_Comm.

For The_PLC_Kid: Cost is not the only issue to avoid using Ethernet switch. As the connections between racks should be the PLC internal data exchanges, we want to avoid somebody trying to connect to that network (Usually with the Ethernet switch - people have a tendancy to connect when they want to access to the network). Another thing is we do not want the process to jeopardise due to an external component (Like Ethernet Switch) failure.

Regards,
--Rahul.
P.Eng, TUV FSEng

The simple answer to that silliness, is don't use Ethernet. Use ControlNet instead, and leave an Ethernet module in there so you can connect to the system easily.

 

[The Plc Kid]

The simple answer to that silliness, is don't use Ethernet. Use ControlNet instead, and leave an Ethernet module in there so you can connect to the system easily.

Is the controlnet chasis to chasis connection faster or more reliable? Or is that just because it is less likely to be tampered with than the ethernet connection?

Does seem that using controlnet would be less likely to get fooled with vs ethernet.

 

[elmatador]

Controlnet is the way to go between chassis. It's definitely more secure. Also the controlnet scheduling will guarantee the data for your i/o based on the Rpi configuration. Typically you go trunk based system with coax controlnet connections. You can actually make your controlnet in a ring topology with fiber modules which will make it even more solid. Don't over complicate this too much.