valdaz

DVP-12sa2 modbus

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Hi, PLC DVP-12sa2 connected via modbus COM2 to HMI OP320-A (china clone) outputs Y0-Y3 are working, inputs are working only two X0-X1, X2-X7 is not working what could be the problem?
Thank You

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Posted (edited)

If you are able to connect panel to the PLC then the link is OK. I didn't get what are you trying to do - activating outputs and reading inputs of the PLC from the panel? 

Edited by IvanBratanov

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Hi, thanks for the reply. I want to activate plc outputs and read inputs from HMI

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So if there was a problem with the RS-485 link between the PLC and the HMI, none of the I/O points could be readen or written. If only few inputs are unable to be readen, the problem should be in the screen objects representing the inputs (the lamps). If inputs X0-X1 are readable and X2-X7 are not, perhaps you should compare the properties of the lamps reading the status of X2-X7 with those reading X0-X1.

If it still does not work, try the following:

You may also try to change the data format. I'm creating projects based on Delta IA equipment and I'm always using Modbus RTU 8N2 data format (you used Even parity check instead). You may also try higher baudrate. Be sure that both device have same settings (except station address of cource:)).

Try 8-bit mode as well (add SET M1161 instruction to the initial rows of the PLC program).

 

I don't believe that the problem is in the PLC but try to check if X2-X7 are OK (LEDs of X2-X7 should lit when they are activated). You may also create a test PLC program like the one attached here. Y0 output will be ON when some of the X2-X7 are ON. If the Y0 LED lits when activating X2-X7 inputs, PLC is OK.

test.JPG

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Hi, I tried your suggestions but did not help, PLC with OPC works as it should, I think the problem is OP-320A, change it to DELTA TP TP04G I think will work. thanks again for the help.

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Posted (edited)

Reading and writting I/O points of PLC from HMI is a basic elementary feature, one of the most easiest things you can do, it should not make troubles if both devices are OK and properly connected. 
As I mentioned above, reading inputs registers will work if screen objects are properly set - for example input X5's screen object (the lamp in your case) should be multistate type object and should read condition of register X5 of the PLC via the RS-485 link.
TP04 series is alphanumerical screen model, I would use DOP-107BV graphic screen model. I've used it already in my projects many times, it's cheap and reliable basic HMI and has more features and is more comfortable. I think it will be more suitable for education purposes.

You could write here if you have future difficulties....
 

 

Edited by IvanBratanov

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