Modbus in Vision V700

[Justas Grinaveckis]

Hi, I'm having hard time displaying data on V700 PLC. After MODBUS config and reading holding registers HMI still shows 0. Do I need to write data to data table and only then display on HMI? Data has to be read from MIO 12-V I/O module. Network ID matches, start of vector links to hmi variable. What could be done or I did wrong? Thanks. I'm attaching vlp file here

[Ofir]

Hi,

There is no attachment file here.

Are you using MODBUS TCP or RTU? 

You will need to check that the communication settings are properly configured (Baud rate, parity, stop bits etc.. IP address, port)

Check also the value of the status register that is linked to the MODBUS command - this can tell you if the problem relates to communication , register address, etc..

 

[Justas Grinaveckis]

5 minutes ago, Ofir said:

Hi,

There is no attachment file here.

Are you using MODBUS TCP or RTU? 

You will need to check that the communication settings are properly configured (Baud rate, parity, stop bits etc.. IP address, port)

Check also the value of the status register that is linked to the MODBUS command - this can tell you if the problem relates to communication , register address, etc..

 

I'm using MODBUS RTU. The tricky part is that baud rate, parity, stop bits, slave ID and port matches perfectly.

I will try to check status register using online test.

One more question - if I'm reading only one register from slave, can I display measured variable on HMI at set time frame? for example every 60 seconds it asks for measurement and refreshes last one.

[Joe Tauser]

You don't need to write the Modbus data to a Data Table.  You can display link it directly to the display with a numeric indicator.

The display updates every PLC scan, but the value on the display will only update when it gets new data.

You need to post your code - it sounds like you're having trouble configuring HMI display elements.  We can help if we have something to look at.

Joe T.