Rotary table WEISS Labview

[henk1000]

That is the Python code. It works for me. I have tried 3 libraries of Modbus in Labview including the NI Modbus library. Tried writing to single registers, multiple registers, coils, etc. Device number, time out, address, etc.
Always comes with an error when Labview executes the block to read.

[pincpanter]

So please post the NI Modbus free library version and describe which error and where, so we can check it.

[santo_13]

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@henk1000 wrote:

That is the Python code. It works for me. I have tried 3 libraries of Modbus in Labview including the NI Modbus library. Tried writing to single registers, multiple registers, coils, etc. Device number, time out, address, etc.
Always comes with an error when Labview executes the block to read.

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Seems pretty simple enough, please attach your LV code to see what could be the problem.

from pymodbus.client import ModbusTcpClient

def read_modbus(client, a, b):
    """A dummy docstring."""
    v = client.read_holding_registers(a,b).registers
    position = hex_to_dec(v[0], v[1], 10000)
    speed = hex_to_dec(v[4], v[5], 10000)
    torque = hex_to_dec(v[8], v[9], 1000)
    motor_state = v[12]
    print(f"position: {position}")
    print(f"speed: {speed}")
    print(f"torque: {torque}")
    print(f"motor_state: {motor_state}")
    
def hex_to_dec(reg1, reg2, factor):
    """A dummy docstring."""
    a = str(hex(reg1))
    a = a[2:]
    b = hex(reg2)
    b = b[2:]
    c = "0x" + b + a
    c = int(c, 16) / factor  # normaly 10000
    return c

def writeModbus(client, a, b):
    """A dummy docstring."""
    try:
        write_to_motor = client.write_registers(a, b)
        assert not write_to_motor.isError()
    except ConnectionError as errorcom:
        raise SystemExit from errorcom

def modBus():
    """A dummy docstring."""
    try:
        client = ModbusTcpClient('192.168.1.200', port=502)
        print("Modbus connected")
    except ConnectionError as errorcom:
        print("Can not connect to PLC!")
        raise SystemExit from errorcom
    return client

connect = modBus()
read_modbus(connect, 60, 13) # Read from 60, 13 registers
writeModbus(connect, 0, 1)   # Write on register 0, value 1

connect.close()

[Jay14159265]

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@henk1000 wrote:

That is the Python code. It works for me. I have tried 3 libraries of Modbus in Labview including the NI Modbus library. Tried writing to single registers, multiple registers, coils, etc. Device number, time out, address, etc.
Always comes with an error when Labview executes the block to read.

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Well if you are having so much trouble with the LabVIEW modbus libs and the Python modbus lib works, just call the python code in LabVIEW with a python node, see here in LabVIEW for examples:

 Examples for using the Python Node are available in the LabVIEW Example Finder (found in Help >> Find Examples...) under Communicating with External Applications >> Using External Code >> Integrating Python Code.

Or if you must make it work in pure LabVIEW, post the error that you got. 

[LVNinja]

Ask them for the MODBUS protocol. 

[henk1000]

That's what I have been doing, but would nice having only the Labview application.

[henk1000]

[Jay14159265]

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@henk1000 wrote:

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Thanks, that helps. Error 56 is a timeout error: 

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019Lz2SAE&l=en-US

[Jay14159265]

I don't have that modbus library, can you set the timeout? 

[LVNinja]

What happens if you try this ?