AB Powerflex 400 modbus addressing

Hello, all I am hooked from an idec PLC to PF 400 Drive and need to read and write data via modbus rtu over rs485 I got it all hooked up correctly but its been 2 years since I had a scadapack hooked to 3 of these drives and talking and cannot remember the addressing. PF 400 has Address (Decimal) 8192 for writing logic commands but what is that in modbus? Stupid question I know, but I dont remember how AB uses their parameters and how to read and write to an address like that. And now I am using a different type PLC.

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/22c-um001_-en-p.pdf

All of the Modbus spec starts at page 181 (appendix E) of the user manual.

When the PowerFlex 4-series user manuals refer to "Registers" they mean Modbus Holding Registers, which are commonly referred to as "40000x" registers because old Modicon controllers prefixed a "4" to the Holding Register memory.

So Register 8192 (decimal) is "48192" in Modicon addressing.

More specifically, you will use Function Code 0x06 (write Single Register) with offset 0x2000 (hex) = 8192 (decimal) to write to the 16-bit Command Word.

Appendix E of the PowerFlex 400 User Manual is the best reference to keep handy for this.

Yea ive been up and down the manual i was just wondering about their decimal addressing i guess 8192 = 48192 or 48193? since idec is offset buy one i believe.

Yeah, the 0 vs. 1 offset thing is a notorious issue in Modbus.

In the PowerFlex 4-series drives, "register 8192" is based on the first register having an offset of zero. 8192 decimal = 0x2000 hex, so if you looked at the Modbus data in a serial analyzer you would see "20 00" in the Offset field.

If you're dealing with a controller that considers an offset of zero to be "Modbus Register 40001", then the Command Word is "48193" and the Speed Reference word is "48194".