Yes, just to confirm...
The new Logix controllers count the number of Ethernet Nodes (devices) added to the I/O Configuration, as opposed to the older method of counting the number of Connections per device.
Any device, such as a drive, distributed I/O adapter, local Ethernet I/O module (1756-ENxT), remote controller, etc., will indeed use up an Ethernet Node. So for the L1, with a 4 Node limit, it is somewhat geared toward smaller applications, such as yours.
Any device not in the I/O Configuration, such as PanelView terminals, programming workstations, Explicit Messaging, etc., will not count as an Ethernet Node, but will use up some Connections. But with the aforementioned 256 available Connections to the L1, this is a relatively moot point.
As Donnchadh has pointed out, consider everything you are likely to add to the I/O tree, other than the drives, and if there are other devices, then count them against the limit of 4 Nodes. If just the 3 drives then you look good to go.
As listed above, the programming workstation, i.e. RSLinx Classic, will only use Connections and not a precious Node. As long as you have plenty of Connections to spare you'll be fine.
Donnchadh,
Interesting to note the new PanelView 5500 terminals and how they can be added to the I/O tree. I just mentioned the new HMI Button Control (HMIBC) instruction in another thread last week. You add the PanelView to the I/O tree in order to have a monitored connection so the instruction can reset the program tag should the connection become unreliable.
Adding terminals into the I/O tree will become the norm as these advancements are made. So we should start getting used to counting them against the Ethernet Node limit when using them with the newer Logix controllers.
I've posted this technote a few times here since the 5370 CompactLogix were released. It's a good explanation and confirmation on what we're describing...
474754 - CompactLogix 5370 Nodes on an Ethernet/IP Network
Access Level: Everyone
EDIT:
GaryS said:
Check the manual the L16 only supports 4 nodes and the PC will use 2 of those...
Gary, where does it say that?
Only devices added to the I/O Configuration tree count against the Ethernet Node limit. The programming workstation is not added to the I/O tree and so should not take up any of the available 4 Nodes here. RSLinx Classic will indeed use up Connections when going Online, etc. Are you mixing up Connections with Nodes? They are not the same thing.
EDIT2: As CLXlifestyle says...
Regards,
George