Reading data using Modbus RTU

[GerdW]

Hi bestecf,

why do you connect a device using a RS485 port to a device dedicated to RS232 ports?

Does your hub support RS485?

[bestecf]

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@GerdW wrote:

Hi bestecf,

why do you connect a device using a RS485 port to a device dedicated to RS232 ports?

Does your hub support RS485?

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I created this drawing by looking at the device. Yes, I noticed the part you were talking about. Because the hub does not support RS-485. I thought the ORDEL PC771's rs-485 output was converted to rs-432 on the port. Afterwards, connection to HUB was provided. I think this is the case if possible.

In Labview, should are being MB Serial Example Master.vi and MB Serial Example Slave.vi run at the same time?

(But, 1 COM Port is used )

[bestecf]

Again hello, I continue. 

Purpose: Read value from temperature display device with MODBUS RTU Serial communication. 

I attached .vi that I tried. Baud rate: 9600, Parity: even, slave addr: 1

1) What should I change or add to read data and show data out ?

2) When I put serial usb cable, there are multiple options in VISA. (COM1-COM11-COM10-COM2) 

How do I know which com port the data flows to? 

[bestecf]

I guess LabView 2019 version is not open. Can you see my problem onto this screenshots? Thanks.

[GerdW]

Hi bestecf,

I guess LabView 2019 version is not open.

LabVIEW2019 is "open" - but as it is rather new (just 3 month) not so many people have it installed yet (including me).

Can you see my problem onto this screenshots? Thanks.

No, as there is no error visible in your images.

Do you get any error when running that VI?

[bestecf]

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@GerdW wrote:

Hi bestecf,

Can you see my problem onto this screenshots? Thanks.

No, as there is no error visible in your images.

Do you get any error when running that VI?

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In this vi, there is no error yes. But, there is a purpose that needs to read value from temperature display device with MODBUS RTU Serial communication. 

Baud rate: 9600, Parity: even, slave addr: 1

1) What should I change or add to read data and show data out ?

2) When I put serial usb cable, there are multiple options in VISA. (COM1-COM11-COM10-COM2). How do I know which com port the data flows to?  

[GerdW]

Hi bestecf,

1. Read the manual of your device. It should contain the information you need…

2. Read the manual of your USB-Serial converter. It should contain the information you need.

2a. Test each COM port for responses of your device when you send a command…

2b. Why are there 4 COM ports? Does your USB-Serial converter provide 4 physical ports?