Modbus RTU help

[Beginer]

Hello,

I purhased homebuilt instrument consisting of 16 Temperature controlers. All I nead is to log temperature data in a table (time, temperature) for each thermocouple.

The instrument manual states that I should read:

- adress 0x0060     1 register (2-bit)    temperature value x 10       Read only.

- adress 0x0062     1 register (2-bit)    Input signal status (0-OK; 1-underrange; 2-overrange; 4-underhilimit;5-overhilimit)       Read only

- adress 0x0064     2 registers (4-bit)  temperature float value (IEEE format)      read only

baud rate: 19.20

stop bit:    1

Parity: none

I have almost no experience with LabView. I downloaded modbus library but don't know where to start (all exapmples state how to read analog input but after some reading i think my adresses are digital). Please help.

[K C]

Hi Begin(n)er,

First of all you should post this question at the labVIEW board or the Instrument Control board and not at the DAQ board.

If you want to use a programming language as LabVIEW I suggest that you follow a course and/or read some books.

ModBus registers are always 16 bits that is 2 bytes. Not 2-bit as you say.

It makes no difference is the source of the data is digital or analogue. It is still MB data.

With the NI MB lib you can read registers. You have to extract the bits and convert the data for your presentation.

[Justin_E]

Hello,

You may want to take a look at the Learn LabVIEW 8 in 3 hours Developer Zone Tutorial if you're new to LabVIEW. 

For Modbus communication, the Modbus library actually provides a couple examples that might help get you started. First, open up the Functions palette by right-clicking on the block diagram, then navigating to User Libraries -> NI Modbus . From here, you can select from 2 pairs of examples : MB Serial Example Slave and MB Serial Example Master, or MB Ethernet Example Slave and MB Ethernet Example Master. Keep in mind that these examples are designed to run simultaneously (e.g. MB Serial Example Slave and MB Serial Example Master both running), and that they might not work perfectly for your application. However, they are a good starting point for getting started with Modbus communication.