Hitachi SJ200 and ModBus Control Problems
 

As you may already know Tony and I are trying our hands with a Hitachi SJ200 VFD. We have the unit working with no problems with the keypad, start stop the spindle and any speed set with the pot.
Now if we connect it by ModBus with in Mach3 Config ModBus the <Test ModBus> I'm able to write and read both Coils and Holding Registers with no problems except when issue the coil 0001h Run command and the 0002h Direction Command the VFD goes into Alarm mode and needs to be reset to clear the Alarm code.

The only Settings change are A001 and A002 to 03 so that it's now using ModBus and the 485 switch has been selected.

SJ200 VFD Settings
A001 = 03 Frequency Source Setting
A002 = 03 Run Command Source Setting
A003 = 400 Base Frequency Setting
A004 = 400 Maximum Frequency Setting
A044 = 00 V/f Characteristic curve Selection
A082 = 220 AVR Voltage Select
C071 = 06 Communication Speed Selection
C072 = 1 Node Allocation
C074 = 0 Communication Parity Selection
C075 = 1 Communication Stop Bit Selection
C076 = 02 Communication Error Selection
C078 = 50 Communication Wait Time

Any help would be much appreciated
Regards

Paul (Skippy)
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Paul

One thing I have learned after much head scratching,

Run is 0000h and direction is 0001h.

0002h is the register to send an alarm command.

I know...I know......that is not how the Hitachi manual reads.

As soon as I stopped sending a 1 to 0002h, the VFD stopped going into alarm condition.

In fact the only coil register I send, is a 1 to 0000h.

The default direction (CW) is all I need anyway. So no need to command that. (0001h)

Greg

Have you tried a 68 ohm resistor?
Sorry Skippy just could not help myself !!

Ross

Lol !! now now boys :D
Cheers
Tony.