Limited register response using hitachi x200.


Thread Starter



I try to control inverter hitachi x200 via modbus using PC and unitronics V530.

To test connection i use Modbus Tester and i can freely turn inverter ON/OFF and change frequency, but I am limited to see only first 8 registers. When i choose to view data of more registers program send exception error - 02 illegal address, and I have response only from read holding registers. I need a lot more than that so I ask you for your help. It may be connection problem, because when I use V530
(PC -> PLC -> inverter)

I have some connection errors - it retries connection all the time, so if anyone had tried something like this, I would be grateful for any advice.

Best regards, Jacek
Unitronics issue with comm retries? RS-485 reflections from cabling's impedance mismatch?

I notice the Hitachi uses an "RS45 modular jack" (apparently an an RJ45 connector carrying RS-485). Hitachi provides no internal termination resistors.

Did you split apart the CAT cable to install a termination resistor?

Unitronics uses "jumper settings" (DIP switch?) to put a termination resistor on the RS-485 line
RS485 with termination is 1 = A, 2 = A, 3 = B, 4 = B

which registers do you want to read?
I guess that you requested D001-D007 on address 0x1002 to 0x100A?!
=> starting address = 0x1002
=> quantity = 8

If you request more than 8, you get out of the specified register mapping: there is no register on address 0x100B!

Try to make multiple requests for non-contiguous address ranges.

source: X200 Series Inverter Instruction Manual (B-22 respectively pdf page 264)