AB Micro 800 MSG to Powerflex 525 - Real

I am trying to communicate to a Powerflex 525 using a Micro 820 using a MSG instruction over Ethernet. I am using the position UDFB from the AB site. I need to write a few separate MSG's along with the UDFB. I want to change the parameters that define my position steps....


I found a read/write download from AB (Document QA20415) This MSG instruction is set for USINT. I need to write a REAL value. Any idea how to change this without rewriting the constitution?



or


Does anyone know how to add a read or write to an existing UDFB? It would be nice to just add it to the position block from AB. I am concerned about running the UDFB and the MSG at the same time...



Thanks in advance, Chuck

I believe to edit a UDFB you need Connected Components Workbench Developer Version. Standard version will not let you edit a UDFB.

For the data type, you might want the "Copy" instruction, COP. You use it to copy each bit from the REAL variable to each bit in the USINT array. Basically the data sent by the message (for a message "write") will be "broken up" as an array of USINTs but it is really just a collection of ones and zeros. The data from one REAL would fill two slots in the USINT array, so your length for the COP will be 2.

Also check the VFD documentation to see how the REAL is treated in the drive (for example, maybe to command 54.32 you send 5432 to the drive). In that case you would not use the Copy instruction, but would just put 5432 in the USINT to send to the drive.

Minor typo: I think USINTs are 8-bit integers (0-255; S => Single-byte) so there would be four COPied per 32-bit REAL.