What happens to the clients if they lose the connection to the server? Will the client still be able to control the PLC? The system design we have is 12 stand alone machines each with their own PLC and touch screen they all run separate from each other. We are proposing to install a server with Ignition to handle the 12 clients but one question that came up was if the network went down would the clients still be able to control the PLC. Keep in mind that each machine has a 4 port switch, 1 port for the HMI, 1 port for the PLC, 2 ports for the network ring in and out. So if the ring went down will the HMI still be able to control to the PLC? I realize that i would lose database function but would still like to have control
Communication to/from the PLCs is done only from the Ignition gateway.
If your clients lose communication to the gateway, or the gateway loses communication to the PLCs, then you will not be able to read/write from the PLCs.
Perhaps an architecture different than what you’re proposing would help. I think this kind of situation may be a use-case of the Ignition panel edition licenses…
I believe that he is proposing an architecture like the emergency one where each terminal is running it’s own local copy of panel edition (free). The idea is that one central licensed copy of Ignition runs a project that can access/control all 12 of your machines (plus do graphing/reporting/alerting/and whatever else) and run as many clients as you want (and support “retargeting” from any of those 12 local terminals to access the extended feature set). In the case of a network or other failure, the local terminal can run its own panel edition project to directly control the connected PLC/machine. Depending on how you do data logging, you may want to consider licensing a limited SQL bridge module so that you get the benefit of continued store and forward logging in the event of a network outage. The distinction is that each node would write to the central database as opposed a single Ignition gateway polling each PLC from the network for central data logging. There is no difference once the data is in the database. The second option is especially relevant for stations that are connected with unreliable or intermittent network connections. You can even leverage that approach to do batch writes by design.