Hello Team!
I have a small supervision system that I've been working on lately. Briefly, it constitutes of monitoring machines here in the power house.
Most often, when a connection to one of the slaves (control modules) is lost, the values previously captured by my supervision board just before the incident occurred, will be retained until the connection is restored. This often cause operational issues as the operator might not notice the sudden lost of connection to server and which ensue leads to lost of data.
Now my problem is, I would like to listen to connections to the server with a node or flow and perform the following;
When the connection to the server is active, it returns all the real or actual data.
When the connection to the server is lost, it renders all data to zero.
I believe this way, the operator will easily identify connection loses and restore them in time to reduce data lost as the result of poor communications.
I have not done anything yet to resolve this because I don't even know where to start.
Any help on this is greatly appreciated.
Thanks in advance..
What node type is receiving the data from the slaves?
[Edit] You used the term 'slaves (control modules)' and then talk about connections to a server. Are the slaves the servers?
Also where is node-red running? In the Supervision Board?
Your description seems to imply that you will receive data from the Nodes on a regular schedule and that this is known in advance
If this is the case then you should use a Trigger node that will reset at a period greater than the time between messages - if a new message is not received the trigger node could either set the dashboard values to zero - or perform some other sequence of events to alert the operator that data is stale and there is a potential problem
My bad. The slaves are actually the control modules of the machines. They're all connected to a single server. The connection lost here is referred to a connection lost between a server and one of the control modules. I am using dashboard 3.6.5 to run the nodes. Just decided to call it Supervision Board.
Please try and answer all the questions. In particular I asked:
That will at least give us a clue about the comms between node red and the control modules. For example, perhaps you are using Modbus, or perhaps the modules have an http API that you call, or perhaps the modules call an http API in node red, or perhaps they communicate using MQTT or one of the proprietary automation protocols. Without information on the comms technique it is very difficult to suggest the best solution.
