Modbus Confirmation Message
We have a client that controls water pumps through Mango. When setting RPM or Start/Stop bits our client would like to display on a dashboard the date/time that the Modbus device confirms it received the command.
I've been searching the forum posts and documentation, but can't find anything about how to get this information. I'm guessing the Modbus data source events are tied to the confirmation message, but I don't see anything on a positive confirmation.
Could you give some guidance on this as to if/how we could get this data?
We're using Mango 3.7.7. Let me know if any other information is needed.
Forgive me if I've got this wrong. But isn't modbus a master/slave set up?
In that case, assuming the mango is the master. there's no confirmation. the unit merely acts upon the command received?
If you're going via a plc to your pump control. Can you not make it send a logic response upon receiving a command? Alternatively, perhaps polling a specific register that changes value depending on the command received and using that to your nearest n seconds time received...
Sorry that's all that I can think of that you may be able to work from...
That is an interesting question. The device does respond with a confirmation message after a write but I don't think there is any way to display that it was received. On the Data Source, there is a Write failed event that you can use if there is a failure in a write command.
If the write is successful the timestamp of the confirmation will be the last update of the data point. As Matt suggests you could set up different ways to handle this with logic in the PLC
Thanks, Joel and Matt for the replies. I'll try to put something together based on what you said.