Modbus RTU

Dear Sir/madam

I Am using Indusoft Web studio with Quite A trust.

But I am facing a problem. As I want to configure power analyzers (Qty = 16) through Modbus. All the power analyzers data is showing in the indusoft web studio.


The problem is that In some time some power analyzers data vanishes and show “ ???” marks sign as unreachable and then back again within 2 seconds . it is showing in the random basis not for a single power analyzer or few power analyzers.


any help will be appreciated.


Zubair Ahmed
  • First of all you should check on the output window the driver response (field read commands checked). When you have question marks the window should write the response of the device.
    The most common solutions are:
    The modbus serial rs485 network is not well designed (resistors missing, noise on the network, the grounding is incorrect, the 0V potential (not A and B) is not connected.
    The polling may be too fast for your network, try to use a tag on the "Enable read on idle" that is configured on the scheduler as timer to slow down the polling repetition.
    One device may producing noise on the network, identify it and attach a network isolator or repeater.
    The network may be too long in meters, do a better design including isolators and repeaters.
  • Dear Stavros_d

    thanks for your reply.

    none of the solution provided by you is worked. but at least you replied among thousands of people.

    i solved the issue . infact when i convert rs485 to rs232 . then rs232 supports slow data. so i have to configure the indusoft slow data rate plus tries more instead of showing out of range.

    this solution worked perfectly . now i am fully satisfied. thanks again for your reply .