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Connecting SM70-J-T20 to Moxa I/O E1212 module

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I'm a complete beginner to the topic so I apologise in advance if my terminology is lacking. I'm trying to create a simple application using an Unitronics HMI+PLC SM70-J-T20. I have created necessary logic for the program to work, but now I'm at the point of trying to send signals initialized within the program to a Moxa E1212 I/O module. From what I have gathered, there is no way of operating on the I/O directly through VisiLogic and the only way of communicating with Moxa is through MODBUS IP and addressing of the I/O. I have set IP of the I/O module as well as the HMI according with my local network based of my computer ethernet card. Unfortunately the SB 150 stays at the value of  0.  It may be a total non-sense, but I think this means devices are not connecting. I have attached a snipet of the code that is supposed to connect them to each other. Is my syntax or/and understanding of the topic correct?
Thank you so much for any input!


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  • MVP 2023

MB 29 in rung 2 needs to be a direct contact, not a positive transition. That may or may not solve your problem, but start with that.

Also, are you connecting the PLC to the I/O through a hub, or a direct cable connection? If the latter, be sure you are using a crossover cable. If using a hub, connect your PC to the hub and make sure you can ping both devices.

Thirdly, I notice you are using port 20257 for both the master and the slave. That's okay, but are you sure your slave device is looking for a connection on port 20257? In my experience slave devices of this type usually use port 502.

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You used normal open contact SB 168.

It not referenced this way in  any recommendation.

Preferred to use power-up value "set" for SB 168.

Set SB 168 warrant you restoring LAN link when LAN cable being disconnected then connected again.

Other recommendation is to init all 4 sockets to default settings (explained in Help).



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