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Hello sir.

Thank you the door is now closed. ?

I have tried what you said to push and reset the e-stop on start up.

I even tested the power supply into pin 2 at 23-24 v. the power is reaching the pin just fine. I tested it many times.

the e-stop alarm will not stop flashing. the tower light is also on.?   Is there anything else I can try? is the way I have the wiring correct as i have it in the diagram?

I even switched the pin plug for pin 1&2 for pin plug for 3&4  with no luck.

I know it is probable something simple. I just don't know what it could be.

the Masso controller powers up fine. all my wires are tinned and strong current is continuous.

please help me?  ...I have been trying to figure this out for some time now.




  1. Whats the voltage you getting on Pin2 of the estop connector and -ve of the power supply when measured by a multi-meter, when you press and release estop.
  2. Have you connected an MPG pendant to MASSO?
  3. Can you please goto the F1-Setup screen and see that the EStop signal changes between L and H when you press and release estop as per the below:
Quote from GOK on May 5, 2018, 8:50 am

Thanks for getting back to me.

so I should press and reset before the masso logo comes up?

and will this be something I will have to do going forward?


Estop needs to be pressed or released when you see the flashing message on the screen. The flashing message will tell you either to press or release the estop.


  1. I have not connected a mpg pendent... no money yet, sorry.
  2. The voltage into the e-stop pin 2 is 23.6 V - 24.0V and when the e-stop is depressed the voltage is 0.0V
  3.  The input does not change at all when the e-stop is depressed. or up.  it stays at L
  4. in-fact I am a little depressed now. 🙂

the pin plug does not seem loose, or any more so than the other plugs? everything seems normal.

I am treating the controller with kit gloves (extra care)

I double checked  both things to verify.




  1. Thats fine if you do not have a MPG, everything will still work, I just wanted to check because estop wiring is slightly different with MPG.
  2. I think you might have burnt the opto isolator for the estop input, but dont worry as we can easily use the other spare ones on the board.
  3. Can you please remove the front cover/label and slide out to the left.
  4. Next see this link:
  5. From the above link remove the E-Stop opto number U46 and replace it with U1 opto
  6. Please give it a try after this and if the opto was damaged then your estop will work.


sorry friend... I swapped the opctocouplers. but had the same results.

keeps flashing whether the e-stop is depressed or not.



Can you please connect the estop signal to input no.8 on MASSO and check that that input changes between low and high with the estop button.

Hello again

yes, I connected  to the input 8 and input 8 switched  from L and H  upon the e-stop switch being depressed.



So that means that something on the estop input is damaged. Whats you controller serial number please and where are you based?


Serial No. 5A-2131  George O'Kane.

I am  at South Easton MA, USA.

the controller came in the foam package? everything looked on the up and up.