I have a Unitronics JZR16 Jazz2 controller I've programmed to run a simple air ventilation system in my house The thing is running great btw. The focus here would not be the entire protocol but just start with understanding the memory map in Modbus and some of the basic function calls.Pages. I highly suggest you read up a bit on the basics of Modbus first before you dive in and try to communicate. Although the register def file is pretty cryptic a nice secret decoder ring would be niceit looks like address 1 through 35 can be accessed with a read function and through from a write holding registers command.
You could use a known Modbus master like Modpoll to help you troubleshoot the communication. I would first try to read 1 word at the first address and see if you can get some data from the device. How Do I Communicate to a PLC Using LabVIEW? The examples that ship with the NI Modbus Library are probably not going to work without some modification to the reading and writing. Next thing to find out is if the unit your trying to communicate to is a master or slave. Such as in the attached text file above, is to read the software status, how should this command be formatted and inserted in the code. Are you plugged in on both ends?Īre you plugged into where you think you are? Do you have a null-modem cable when you need a strait-through or visa-versa? Is the device on? It times out trying to read discrete inputs. You should get error messages if you are talking to the device. Timeout out with serial would tend to indicate to me that there was no response.
#Labview modbus rtu how to
I'm not sure how to format the command or how to incorporate it with the modbus library vi. I do not know how to pass info to the unit and receive feedback.
I have attached a list of register defintion here. If there's an existing code that someone has that works on their end, then it will be helpful for me to troubleshoot it. I'm new to this so not really sure where to start troubleshooting. I ran the example VI in the library and I am getting "Timed out" errors. I would prefer using Serial but there is TCP option as well. It'll be great if you can share the code.
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