MOXA, RS-485, ModBus RTU

[pitol]

Then it's not a LabVIEW issue.

You have to sort out your issues with communication.

Can you provide a print screen of a communication settings from Performance Analyzer tool?

[Gadjetins]

I hope I understand you correctly )

[pitol]

It looks like the tool you are using is just for RS-485 com, not Modbus.

Try to use MODSCAN. It will allow you to poll for Modbus registers.

You can download eval version here: https://www.win-tech.com/html/demos.htm

[Gadjetins]

 I tried to configure Modscan itself, but I still get a Modbus Message Timeout error.

Could you explain to me how to properly configure the connection in modscan? Please  )

[pitol]

You need to configure two things:

1. Communication parameters:

Where you need to configure BaudRate, Word Length, Parity, Stop Bits and COM port.

2. Modbus Settings

Where you need to configure Modbus Registers.

MODSCAN address is your regular address + 1. So if you want to read register 18 you need to type 19 to the Address field.

Be sure that Device ID matches your device's Unit ID.

Length should be set to 1 and 03: Holding Registers set.

Check if it works.

If not, check you cabling, device or anything in between...

[Gadjetins]

Thank you! as I will check I will unsubscribe to you, but most likely on Monday.

[Gadjetins]

I can not configure through modscan, I do not understand where to get the id of my device. I tried to contact again via modbus poll (the result in the picture). as a result : the modbus poll contacted only device I didn't figure out which one as there are 5 pieces and they soedeniny consistently.

[pitol]

It looks like the communication works fine.

The ID of the device is 1.

The picture you sent states that Baudrate is 57600 not 9600 what you said earlier.

Try your LabVIEW code now with he same communication parameters you used in Modbus Poll tool.

Port: 4
BaudRate: 57600

UnitID: 1

Parity: Even

StopBit: 1

[Gadjetins]

I changed new master series to new master slave and as a result the error at the end of the program disappeared, but remained at the beginning )

[pitol]

You cannot use Modbus Slave, since you are the Master. Your device is a Slave.

Try to create simple code as attached below: