Modbus Temperature Device (Slave) Display Value different from Labview displayed Value

[Austyno]

I have a LabVIEW code that runs as Modbus master and a Temperature Slave device with a display on it. The problem I have is that the temperature device display is usually greater than what the shown Labview value by 1. There is no mathematical calculation involved in the code except to read a 16 bit holding register address and whose value is just connected to a LAbview indicator. Any help please?

[Borjomy]

what does "usually greater" mean?
Give a list of values (display, modbus). Rounding errors are also possible.

[Austyno]

I mean that the value on the device display screen is more by 1 than the Labview modbus value. Im using labview 2017. Examples are: 819 (Device Display) Vs  818 (Labview),  767 (Device Display) Vs  766 (Labview), 809 (Device Display) Vs  808 (Labview) 

[JÞB]

What is the device?  Do you have a link to the manual? Are those Kelvins, Deg C or Deg F?

Id guess (my magic 8-Ball is pretty good) the device rounds the value and truncates the register- Add 0.5 of whatever unit to the register value and display as integer 

[JensG69]

What does your device manual (BTW: which device, which modbus address) say to this?

Regards, Jens

[Austyno]

The device is a Temp controller. Those are Deg F. Link is https://nicontrols.com/media/pdfs/pixsysatr142usermanual.pdf. Im using modbus register address 1000

[Borjomy]

You can also read at 3001..3016 🙂 then the data must match exactly. And about the addition of 1 ... Maybe it's just a bug.

[JÞB]

Use reg 1100 instead and set the display to show tenths of a degree per pg 42.

You may need to read 1014 as well.

[Austyno]

I read Register 1100 and same Issue existed. Dispay (835)  more than labview value (834) by 1. Register 1104 gave me a different value (382)

[JÞB]

Read the manual again

1104 is setpoint 4

1100 is visualized process (as displayed) 1014 is the CJC temp