Modbus - Working with floating points

[SCADA_Dude]

Is there a way to address floating point variables with Modbus/TCP?

FYI: Using Quantum 434 12U (Unity Pro XL 3)

 

[Peter Nachtwey]

Yes, you read two register for every float. My customers do this all the time.

 

[Singapore_Mats]

normally I send as integer, and scale later.
For example send a temperature as "304" and then divide by 10 to get "30.4"

 

[tragically1969]

They are addressed as %MF, be careful though as they use the same address space as %MW

You also need to make sure you are reading them the right way round, if you are addressing them from SCADA or and HMI there is a usually setting for which way round the words are

Edit: so jst looked at your user name and question again and am putting 2 and 2 togetther and suspecting you are addressing from SCADA, in that case you just declare them as REAL and %MW in the SCADA app (thats if it allows native addressing which Citect does if you use Modnet30) or as its modbus address and the driver will take the n and n+1 address and know its a REAL

 

[SCADA_Dude]

Great, that worked!
Thanks

 

[danw]

declare them as REAL and (SNIP) the driver will take the n and n+1 address and know its a REAL

Is thet term "Real" a synonym for "floating point"? Are the two considered to be the same thing?

Dan

 

[tragically1969]

Yes REAL, Floating Point, both the same thing.