managed or unmanaged?

[mr_electrician]

We would like to set up all our plc's and Fanuc Robots onto an ethernet system and get rid of the old fasion hard wire I/O going between all four plc's and robots. The question came up asking if we would want managed or unmanaged switches? I am not sure which to use and why you choose one over the other. If it helps I have listed what we have for the particular cell we are looking at converting over to Ethernet. 4 seperate cabinets, each with its own Q series plc. One of the plc's have CC Link going to remote I/O 4 seperate fanuc robot controllers. Each have an ethernet option. All the plc's and robots are talking by hard wire interlocking. (many failure points. The robots do not talk directly to each other but only to the plc's. The plc is more like a traffic cop that looks at the robot outputs and then sends outputs from the plc to inputs of the proper robot) We would like to add possibly 4 HMI's to the cell, remove 3 of the 4 plc's, and have the robots on ethernet to plc's and each other. We also would like to integrate remote I/O with ethernet blocks, and also send data onto the server for production counts. Any advise from anyone with experience in this is appreciated!

[kaare_t]

If this is a separate closed network I would just choose unmanaged switches, however if you are connecting this network together with an office network or similar you should use managed switches. In essence, unmanaged switches are "Plug and play" with no configuration needed. Managed switches can be "programmed" to allow/deny traffic between different networks configured in the switch, e.g. one office network and one factory network. That way you can use the same network cables but segment the network into separate private networks (VLANs) separated from eachother using just a switch that can route traffic between the networks depending on your needs. A managed switch doesn't have to be programmed, but if you don't program it you have no use for it and can simply buy unmanaged switches. Here's what I would do if you don't need the complexity of managed networks: 1. Use a separate factory network (a separate physical network which is not connected to the office network) 2. One of the PLC's can contain an extra Ethernet card for the office network so that it can have contact with the office server (alternatively, and probably the best solution would be to use a MES module that communicates with the server) How large is your network today (how many office users, how many factory devices ++)?

[mr_electrician]

"How large is your network today (how many office users, how many factory devices ++)?" Not sure. We do have a building automation system that controls lighting, compressors, etc. etc. and does send an email out to certian people when there is an alarm. It uses a Horner PLC.

[Tech Fred]

If you are already running Building Automation on the same network I would use managed switches. Chances are there are already ones being used. That advantages of being able to control access to network segments and to set up virtual networks will be invaluable as you expand the system. The other advantage is for your IT department. They can monitor the network health and identify issues related to network traffic. They are going to give you the most room for growth.

[kaare_t]

I agree with Tech Fred!