Neuron slow communication with extension modules

  • Hello,

    I implemented my home automation using a Neuron "M303" and five extension modules "xS11". Everything also works as planned. The lamps and the wall buttons are wired directly to the Neuron and the extension modules.
    My problem is that with a quick press of a button, the signal of the input is sometimes not passed to the Evok. Not until the second or third key is pressed. If the button is pressed for a long time (approx. 0.5 seconds), every pulse arrives at the Evok.
    The inputs of the Neuron, on the other hand, can be pressed briefly and quickly, so every signal arrives.
    I suspect that the communication between the neuron and expansion modules is not fast enough.
    Is there any way to improve this communication? Have already tried to adjust the scan_frequency in Evok.conf, unfortunately without success. Which Evok.conf settings are best?
    In which direction is the communication going, do the expansion modules send to Neuron or does Neuron read from the modules?
    Unfortunately I don't find any documentation about the setup of Evok.conf, only what was posted in the forum.


  • administrators

    Hello @walter,
    the reason for this slow response lies in the ModbusRTU protocol itself. The master (PLC) has to poll all the IOs with for all the extensions over slow RS485 bus. Increasing the scan interval will not help much. There are two options:

    1. Increasing the RS485 baudrate. The speed 19200 is reasonable for mid-length buses and you can try increasing it to 38400 or even more. Please, bear in mind, that the higher the speed is, the more communication errors can occur.
    2. Changing the definition of the extension devices in Evok to limit the periodic readings to only the IOs you use, omitting the rest.

    Best regards,

  • @martin-kudláček said in Neuron slow communication with extension modules:


    Hello Martin,
    Thanks for the answer. I've already thought of something like that.
    According to the DIP switch, the xS11 can only have a maximum baudrate of 19200. An increase has led to a loss of communication.

    I thought about swapping my M303 controller for an L303 to have enough inputs on the controller to bypass the Modbus. I then only use the extension modules to use outputs and inputs where speed is not an issue.
    Is it correct that the processing of the internal inputs on a controller (e.g. L303) is a faster method than Modbus?
    Is my approach understandable and sensible, or do I have a mistake in thinking?

    With kind regards

Log in to reply