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Modbus rtu source via tcp gateway, polling trouble

  • hi,

    i have a couple of RTU based I/O units which i reach via a MODBUS TCP/IP 485 gateway device.

    using another modbus master and a polling interval set to say 1 sec, you can see the COMM LED indicators cycling nicely and all is well.

    if i then disable that master and try mango as the MASTER, with a 1 sec update, the polling is very erratic and quite often misses the beat/rhythmn and shortly after comms falls over, with data source might not be updating etc.

    i then have to disable and enable to source.

    i never did get to the bottom of this but as it was the mango wasnt resilient enough to use.

    but i have need to use mango this time so need to nail this issue.

    any pointers as i try to revive this and repeat the problem?

    could the polling be compromised by other sources being lazy?

    if this was the case, i'd still like to see datasource polling by cron, that way the user can segregate sources completely.



  • Hello Skiv71,

    You are not sharing much to follow mango users to help you; I've been using Mango to talk to a host of devices and IOs via Modbus Serial and Modbus TCP.
    I've spent many days trying to figure out how to get Mango working correctly.

    If you could share a bit more detail, I might be able to put you in the right course.



  • hi joohwan,

    sorry i'll try and break it down

    mango (since 1.8.1 i think)

    modbus I/O, RTU via a TCP gateway.

    all i know is it appears mango's polling mechanism is not geared towards multiple sources, i.e. there is no staggering of devices... and i've seen on site where this has risen to unrecoverable comms downtime. resetting the data source or restarting the instance is required.

    2 other modbus masters I have at my disposal, seem to polling 'one at a time' and this works much better