Modbus TCP

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31 May 2020 11:27 - 31 May 2020 11:34 #169506 by charly
Modbus TCP was created by charly
Hello
I have a Optimum BF46 milling machine with the step motor CNC kit
I done 5 years ago a first installation of LinuxCNC and use two LPT port to run it

I try to do a new installation and replace the second lpt port by a wago ModbusTCP coupleur (750-362) on a Debian 10 with Preempt-RT kernel and LinuxCNC 2.9

The configuration is done but the Modbus coupler have curious reaction, each 5-10 minutes all digital output is disable during 1 Modbus cycle add after that normally replaced
Modbus after transmit pause : 17ms
Modbus after receive pause : 111ms
I do a small script in python and pymodbus to do the same think ; in this case, the coupler haven't this bad reaction

Somebody known the cause of this small turn-off digital output during 1 modbus cycle with linuxcnc ?

Thanks
Last edit: 31 May 2020 11:34 by charly.

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31 May 2020 13:04 #169510 by Mike_Eitel
Replied by Mike_Eitel on topic Modbus TCP
Is there a timeout that you can be adjusted in the coupler. Search for a watchdog.
When all outputs get dissabled that points towards a safery feature.

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31 May 2020 13:51 #169515 by charly
Replied by charly on topic Modbus TCP
In coupler, the timeout is removed
The reply state on digital output is disabled, when communication is break/stop, digital output preserve last state
The state of output hal configuration are all of time in good state
That look like at some time an empty tram is sent to the coupler ( and disable all output )
Outputs are reset properly at next cycle

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31 May 2020 14:22 #169519 by PCW
Replied by PCW on topic Modbus TCP
tcpdump or wireshark might help diagnose the issue

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31 May 2020 16:14 #169529 by charly
Replied by charly on topic Modbus TCP
This first test was with modmaster in classicladder
I have reviews all ModbusTCP option and understood fonctionnement of mb2hal
I have redo my config with mb2hal and start a new test

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31 May 2020 18:50 #169543 by charly
Replied by charly on topic Modbus TCP
With the module mb2hal, the coupler wago running well but i don't known why with modmaster option in classicladder that not work

Thanks

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