AB Micro 850 - Modbus Floating Number

yiph

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Join Date
Jul 2017
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Sydney
Posts
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Hi,

I've got a Micro850 which talks to a power meter on Modbus RTU via RS485.

I get a set of WORD data back from the power meter, each data is encoded into two words floating point number.

How do I join the 2 words into a floating point (REAL) tag in the PLC so I can use the information in the PLC?

Is there a function block where I can pack 2 words into a floating point number?

Thanks,
 
Normally you would specify that the data to be read is REAL and it will read two registers at the starting address you specify.


What address are you trying to read and what data type does the manual say it is?
 
Normally you would specify that the data to be read is REAL and it will read two registers at the starting address you specify.


What address are you trying to read and what data type does the manual say it is?

Looking at the MSG_MODBUS function block help, it doesn't mention that you can specify REAL data types? It automatically assigns 125 WORD array to the MODBUSLOCADDR data type.

I'm trying to read address from 30001 for 60 WORD (30x REAL).
Manual of the power meter says that they are in REAL/floating point numbers.
 
Not familiar with the 850's on other Rockwell platforms, you could use the Copy instruction. I see the 850 has a COP block, select the first word as the input, with floating point as the output, length of 1.
 

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