Hitachi VFD Connection

[Aiph5u (Aiph5u (not affiliated with Onefinity))]

Hey Martin,

@MVall

Last one – I think I understand you can’t adjust feeds or speeds on the fly with Onefinity controller.

This is right, the Onefinity Controller and the Buildbotics controller do not support this (yet). (It is a feature requested on both).

@MVall

Any way to at least adjust spindle speed with the VFD to override what the controller is sending and fine tune?

Yes, see below.

@MVall

Was hoping somewhere in that 400-page manual there might be some trick for the VFD to send a signal the Onefinity could recognize and shut down on a VFD or spindle failure, and/or a way to use both RS485 and a spindle speed override at the same time, but I guess that was wishful thinking!

It was not, this is perfectly possible with the Hitachi or Omron VFDs.

Temporarily Overriding ModBus Control on Omron and Hitachi VFDs

For this you have the “Force Operator Mode” (OPE) and the “Force Terminal Mode” (F-TM). While the users of the cheap chinese VFDs have to choose whether they either have manual control of the VFD on the front panel keypad and/or potentiometer, or to leave the control to the CNC controller via ModBus, and have to brachiate through the menus if they want to change this (once for speed control, and once again for RUN/STOP control), users of the Hitachi or Omron VFDs can simply wire a little switch to one of the Intelligent Input Terminals and assign either the OPE or the F-TM function to this input to to be able to use this little switch to temporarily override the assignment of speed and run/stop to ModBus control.

By wiring a little switch to one of the Intelligent Inputs 1-7 and programming this input to OPE or F-TM function, you can switch the selected mode on and off.

• If you use the “Force Operator Mode” (OPE), enabling the switch will divert control from ModBus to control via the front panel keypad (with Hitachi/Omron, the front keypad is called the “Digital Operator”). This mode allows the use of the keys on the front panel to control spindle run/stop and speed.

  Hitachi WJ200 Front Panel	Omron MX2 Front Panel

• If you use the “Force Terminal Mode” (F-TM), enabling the switch will divert control from ModBus to the digital and analog inputs to control run/stop and speed. For run/stop, usually you use Intelligent Input 1 (see circuit diagram below) and for speed you use a potentiometer of 1-2 kΩ. This means that for enabling F-TM, you will not have your little switch wired to Intelligent Input 1 (which is already in use by the “Run” switch), but to one of 2 to 7.

  

Note that if you switch to OPE or F-TM mode while the VFD is in “Run” mode (=when the spindle runs), the VFD will first stop the spindle before it follows the new, manually overridden speed setting. Therefore you shouldn’t do this while the CNC is moving, so while running a g-code program, you should first press “Pause” on the Controller before switching to one of these forced override modes, and resume g-code program only after the spindle reached the new, manually overriden speed.

Note that this, as Alan @Alphonse already reported (thanks to Alan!), also answers the spindle pause problem: With a Hitachi or Omron VFD, during a g-code program, you can press pause on the Onefinity CNC display and control the spindle by switching to OPE or F-TM mode in order to be able stop the spindle, and next morning to switch it back on and resume from pausing the g-code program.

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Weblinks

Manufacturer's page	PDF
Hitachi WJ200	Manual
Omron MX2	Manual