PMDX 126, 107, Ethernet Smooth stepper

[The Contractor]

I recently purchased a PMDX 126, 107 And a Warp9 Ethernet Smooth Stepper. What I am trying to do is install my NPN 3 wire style sensors. The two questions I have are.
1.  Are all the GND pins on J12 connected to each other in other words can i run 1 ground from a terminal block that has all of the sensors GND attached to it. or dose each sensor need it own GND
2.  From what I see in the 126c user's manual the boards max amps out for 12v and 5v is 250ma on J11 and J12. My question is dose J11 and J12 pull power from J18. because I am running a 107 from J18 do my NPN sensors need to have there own power supply. I am powering my ESS from a 5v din rail supply. I do have 12v din that runs the enclosure fans and could use it to power my NPN sensors if needed.

[Steve Stallings]

All the GND terminals on J11, J12, and J13 are the same electrical signal and using a single
connection from one GND terminal on the PMDX-126 to a remote terminal strip that provides
multiple GND terminals to your sensors is fine.

The J11, J12, and J13 power outputs are not drawing from the power to J18, rather all of
these outputs draw power from the same transformer and that is what limits the overall
power output.

Normally the 250 mA available from the PMDX-126 is adequate for a PMDX-107 and all of
your proximity sensors as long as the ESS has a separate power source. Typical sensors
are only 10 mA each.

[The Contractor]

so these are the NPN sensors:
DC 6-36V 300mA NPN NC 8mm Tubular Inductive Proximity Sensor
I am using 5 total, 2 for Y 2 for X and 1 for slaved A this combined with the PMDX 107 drawing 80mA and 3 external Status LEDS 6mA each this seem to me as if it could overload the transformer so I am thinking it my be better just to use external power for my sensors especially because max on J11 & J12 is 250mA. However I could be wrong and I just want to make sure so I don't smoke my PMDX 126

[Steve Stallings]

I think you are misinterpreting the sensor specifications. The 300 mA is the output
current switching rating, not the amount of power that the sensor needs to run.
 

[The Contractor]

Thanks Steve, I can not seem to find any other info on these sensors other then:

Wire Type:3 Wire Type (Black, Brown, Blue). Switch Appearance Type: Cylinder Type
Output Type: NPN NC(Normal Close). Supply Voltage: DC 6-36V.Current Output: 300mA
Diameter of Head: 18mm. Detecting Distance: 8mm. Response Frequency: 100Hz
Detect Object: Iron. Operating Temperature: -25°C to +55°C (Non-freezing Condition)

But it sounds like I should be OK without adding an external power supply. So that's good news. I have been avoiding installing these sensors because I wasn't sure if they would draw to much current.   

[Steve Stallings]

You will almost certainly be ok with powering the sensors from the PMDX-126, and
even if you did have too much load you would not damage the PMDX-126.

I do note that these are NC (normally closed) sensors. The means that you cannot
connect more than one to a single input terminal because they will mask each other
from being seen because opening one does not open the circuit seen by the input.

[The Contractor]

Thanks for the tip that make complete sense.  I have been slowly building this CNC now for a while and bought though sensor long before I decided on a BOB. I probably would not have caught that until it caused huge problems. I should have enough inputs to separate these. I may just replace them with N/O. I will have to do a little more research on what will actually work better or if it really make any difference.   

[The Contractor]

So I was thinking and to save inputs I was wondering if it would work if I run my N/C sensors in series.   

[Steve Stallings]

Series works fine for mechanical switches.

For NPN proximity switches it typically does not work well. Some
brands may play nice, others do not. No harm in trying it, but your
wiring is wrong and/or the symbols for your sensors is wrong.

The emitter arrow of the output transistor in the sensor will be
connected to the Blue ground wire for an NPN sensor. The collector
of the output transistor will be connected to the Black output wire.

I think the Blue of the first sensor should go to GND.

The Black of the first sensor should go to the Blue of the second sensor.

The Black of the second sensor should go to the Pin 13 input on the
PMDX-126.

Please update and re-post your diagram.