I was recently reading a thread here that talked about Ignition and PLC recipes. The thread dealt with the mechanics of getting the data from Ignition to the PLC. It got me wondering about a different aspect of SCADA/PLC interaction.
I am used to equipment having a local library of recipes in the controller. These controllers are older and were meant to be stand-alone, although the do have comms for monitoring by a SCADA system. At some point, I will be replacing the controls with something more modern, likely a custom programmed PLC. As I was reading the thread, it sounded like the situations mentioned referred to a PLC that only had 'one' recipe, the active one. It sounded like the library function was provided by the SCADA system itself instead of there being a selection of recipes in each PLC.
Is this a common arrangement these days? I suppose there are use cases for both situations, but having only one recipe in the PLC would seem to make the PLC programming aspect easier as well as SCADA editing of recipes. Is there much concern for the SCADA system going down? This would seem to leave an otherwise useful piece of equipment with only the current recipe available. Or are most peoples' SCADA systems reliable enough that this is a non-issue?
This is one of those times that I wonder if my limited perspective is skewing my planning process. In my little world, SCADA is something that was added on to the system to help monitor the equipment. Each piece is still fully usable without the SCADA system. The operators use it mostly to monitor what is happening without having to walk around to each item. They also will change a setpoint on a controller remotely, but they are just as likely to change it at the controller itself. The data logs and trends are helpful in diagnostics. Overall, though, the plant would continue to operate if the SCADA system went down.
I'm starting to think that modern SCADA systems are far more integrated with the plant equipment. It's possible that we will head down that road in the future, but I thought it might be interesting to hear how others are currently using SCADA systems.
I am used to equipment having a local library of recipes in the controller. These controllers are older and were meant to be stand-alone, although the do have comms for monitoring by a SCADA system. At some point, I will be replacing the controls with something more modern, likely a custom programmed PLC. As I was reading the thread, it sounded like the situations mentioned referred to a PLC that only had 'one' recipe, the active one. It sounded like the library function was provided by the SCADA system itself instead of there being a selection of recipes in each PLC.
Is this a common arrangement these days? I suppose there are use cases for both situations, but having only one recipe in the PLC would seem to make the PLC programming aspect easier as well as SCADA editing of recipes. Is there much concern for the SCADA system going down? This would seem to leave an otherwise useful piece of equipment with only the current recipe available. Or are most peoples' SCADA systems reliable enough that this is a non-issue?
This is one of those times that I wonder if my limited perspective is skewing my planning process. In my little world, SCADA is something that was added on to the system to help monitor the equipment. Each piece is still fully usable without the SCADA system. The operators use it mostly to monitor what is happening without having to walk around to each item. They also will change a setpoint on a controller remotely, but they are just as likely to change it at the controller itself. The data logs and trends are helpful in diagnostics. Overall, though, the plant would continue to operate if the SCADA system went down.
I'm starting to think that modern SCADA systems are far more integrated with the plant equipment. It's possible that we will head down that road in the future, but I thought it might be interesting to hear how others are currently using SCADA systems.