To communicate over DeviceNet with Fronius, there need to be DeviceNet slave interface that belongs to Fronius. There are two ways this is done according to what i experienced. Electrically both are identical but mechanically they are different:
1. DeviceNet slave belonging to Fronius is installed at the welder (see my attachment). Then you run "long" DeviceNet cable to robot while RS485 network is very short (contained within box on the back side of the welder). This is usual setup. There would be one or two cables from Fronius to robot controller (usually two since power is separate but i was always combining them into one since only powering DeviceNet slave).
2. DeviceNet slave belonging to Fronius is installed in the robot cabinet (your case). Then you run short DeviceNet cable to robot controller and there will be long external cable stretching RS485 interface from robot controller to Fronius. This is what you have. I think it is referred to as an economy version which is probably used as a retrofit when welder did not have DeviceNet slave interface from the start. The RS485 connections are individual wires, white or light gray. in second case they use Amphenol connectors and "long" cable that is obtained from Fronius. This comes in some standard lengths. On the robot controller one must remove one of the plates, drill holes to mount red interface connector that is prewired to EL6021 using those gray wires. This is all prewired, and there is no need to change anything.
Either way - to create DeviceNet connection you need to connect DeviceNet cable from your robot controller to this bus coupler of the Fronius DeviceNet slave and make appropriate settings.
Things to watch for:
1. Fronius DeviceNet node need to be powered from robot controller
2. shielding of DeviceNet cable, need to be grounded in one point only and that means at the robot controller end. if the DeviceNet slave is built into welder, this means disconnecting shield at that end (just pull away the spade and ZIP tie it or maybe put some tape on it.).
3. if i recall default DeviceNet node address is 11 but this is easily changed.
4. use same baud rate on both sides (KRC and DeviceNet slave nodes)
5. different welders/strategies will need different size of IO map. check Fronius documentation or talk to Fronius support
6. as with any DeviceNet bus, pay attention to terminating resistors and supply bus with 24V-ish (normally taken from KRC)
