Author Topic: PMDX 126 REV C, k1 k2 relays.  (Read 1157 times)


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PMDX 126 REV C, k1 k2 relays.
« on: April 18, 2017, 02:07:06 PM »
Hi again, I've been reading how people are using the k1 and k2 relay, and want to confirm my thoughts.  I can run the AC mains active line onto the NO of K1 or K2( and Daisy to MOV on K2), and then run from k1 or k2 COM to the active AC input on my dust extractor / spindle pump etc... and need to use an enable command to send active high signal on pin 1 port 1, to turn 'on' the relay that's No.

Or, if I run live AC in NC+mov( is this needed ) , out Com, then I use a reset active high signal to pin1, to turn off the relay, if reset is active ? And I manually turn them on the first time ?, or after I reset the software reset ?


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Re: PMDX 126 REV C, k1 k2 relays.
« Reply #1 on: April 18, 2017, 03:32:11 PM »
so here is a schematic of what I was thinking...

Steve Stallings

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Re: PMDX 126 REV C, k1 k2 relays.
« Reply #2 on: May 15, 2017, 12:14:07 AM »
Both the K1 and K2 relays will default to off in the power up state
and also any time an E-Stop event happens. You would normally
use the N/O contacts to switch the power to your load.

The power supply for the 70 VDC to the motor drivers does not
need to be controlled by the host computer because a stepper
motor will not run away if the host crashes, and because the
PMDX-126 will prevent step pulses to the drivers if an E-Stop

You do not normally use a relay to switch the mains power
into a VFD because of the high inrush current at the mains
input, and because the VFD will provide low current controls
inputs suitable for turning the spindle on and off. Better yet
you can add a PMDX-107 and control the VFD from that and
also gain variable speed control from G code.

If the H2O pump is for cooling the spindle, I would recommend
that it not rely on an independent control signal as running
the spindle without cooling is a very bad thing. You can configure
the PMDX-1226/107 to control a relay at the same time that it
controls the VFD. Read the section about Multi-Mode usage of
the relays. Or if you do not use a PMDX-107 then use the large
K1 relay to control both the power to the VFD and the cooling

In any case, the small K2 relay's N/O contacts, with the MOV
connected to the N/O terminal, can be used to control the 3A
load for the dust collector.
Steve Stallings