Modbus and floating point data

[Henryp]

I understand that the Modbus protocol does not define a floating point data type but a Direct logic PLC will allow a SCADA system using the Modbus protocol to write a floating point number into the PLC's memory. In DS5 the data can then be displayed as a real double word. The Do more designer will not allow me to enter a floating point number into a Modbus holding or image register. So had do I accomplish what I can do in a DL PLC using a Do more CPU.

[plcnut]

The Do more designer will not allow me to enter a floating point number into a Modbus holding or image register.

Are you talking about DataView?

[BobO]

You can easily put a floating point number into a Modbus register, using either the PUBLISH instruction, or if byte ordering/offset permits, using the float cast operator :R. With the cast option, it must be DWORD aligned, so MHR10:R works, but MHR9:R does not. If it must be on an odd boundary, or the byte/word ordering is wrong, use PUBLISH.

[franji1]

Use SUBSCRIB on MHR's being written to by your SCADA, and PUBLISH on MIRs/MHRs being read by your SCADA.

[BobO]

Use SUBSCRIB on MHR's being written to by your SCADA, and PUBLISH on MIRs/MHRs being read by your SCADA.

Oops...yeah. It does appear that he was looking at the SUBSCRIB side.

[Henryp]

Thanks for the help