MicroLogix 1400 as Modbus Slave

[aryan_iust]

Hi,
I have saved my data, coming from sensors in floating point, in registers F8:0 to F8:21. Now I am trying to use ML1400 PLC as modbus slave and read these registers from SCADA. I have no issue reading integers (N7 table with Modbus address 40001).
However, I would like to know the Modbus address for floating point registers (i.e. the starting address, namely the modbus address for F8:0).
I would appreciate any comment.
Cheers,
Aryan

 

[bernie_carlton]

Use the COP command to copy the bit pattern of the 22 float registers into 44 consecutive N registers in the file you designate (not usually N7) as the 4xxxx series registers. They will have to be recognized (or reordered in a reverse type Copy) by the requesting device as the float values.

 

[aryan_iust]

Thanks Bernie for the response.
So, we can not have direct access to floating point, e.g. F8:0, registers?

 

[bernie_carlton]

With the 1400 as a slave you set up a data file which will be addressed when the external unit asks for a 4xxxx address. I haven't tried setting that to a Floating Point table. I don't think that would work as expected as each F address would have to be two 4xxxx addresses. Or it might skip half of the float values. I don't know, you can experiment.

We just use an 'N' table and COPy in and out and Long or Float values. Bit values can be used right out of the N words.