Modbus dual UINT16 to Float

Ignition
1

Hello,

I am communicating with a Modbus TCP device. I’ve followed the instructions here: http://www.intricatescada.com/main/system/help/About_Modbus_Address_Mapping.html and completed the address mapping.

I am trying to get float values by using the step function in the address configuration from 2 UINT16s. The " Holding Register (Float)" function however seems to use 2 INT16s instead of UINT16s.

It seems the system cannot convert dual UINTs to floats but instead only dual INTs to floats. I would need to convert the numbers from UINTs to INTs and then use the step function to convert groups of two INTs to a float. Basically I need to convert the data type twice, how can I do that?

Thanks

2

The driver does not turn these registers into separate Int16 or UInt16s before making them a Float, so there is no difference.

If e.g. you read HRF1, then the driver requests 2 registers starting from address 1, gets 4 bytes in return, and then creates a Float value from those 4 bytes.

If you’re not seeing the result you expect maybe you need to try the Swap Word Order setting?

3

Hi Kevin,

That makes sense that its using the byte values and not the data type formats, your’re absolutely right, I had the word order reversed after all.

Thanks for your help!