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Wiring a relay to a pneumatic solenoid for mist coolant


Your 60 y/o state of the art technology is hard to find (once a proper description of it is laid out) in the US . this requires a 30-60 day wait for the slow boat from China to show or some really expensive freight.  I am not new to the CNC plasma world my first system was a torchmate that I had running within 2 hrs by viewing their on line documentation (hell it even came with a torch fire relay - wow what a novel concept for a CNC plasma controller..).

Keep in mind when creating online documentation that the system and it's components you are describing may or may not be readily understood or available world wide. Not everybody has the same knowledge of the products you work with on a daily basis. I viewed the WIKI link no where does it or your own documentation say the Masso requires a TTL "high" signal of 5v to fire.

As a commercial user of your product, I need answers readily available so things can be ordered correctly the first time. I don't expect a total rewrite of your documentation overnight however I have seen very little since the Gen 3 was released. I like the features of the Masso that's why I bought it, will I buy again? That's a really good question..




Your lucky living it the USA as you can get your boards from Amazon overnight. I found this when I typed in TTL relay but they won't send to me in New Zealand. I will just need to wait for the slow boat. 🙁

It looks identical to the board I have. I see there are 1, 2 & 4 relay boards on amazon as well though it is the same problem as before with no part number so I agree it is not ideal. The Masso relay board next month will be a great addition and solve the problem but that doesn't help you today. I added a photo of the actual one I have connected to my G3 so you can compare. The only difference I can see is the word PWR is missing and the name FTCBlock has been added thouh I could be missing something.

I added a couple of lines to the TTL outputs page that I think will help users understand. It isn't much but probably all that is needed to explain how it works.  Hopefully make it easier for others in the future.

Cheers Peter

Uploaded files:
  • 20200226_004051.jpg
  1. Its a 6 relay unit.
  2. works on 24VDC.
  3. can handle 5amp current on each contact.
  4. Has troubleshooting Green and Red LED's. If the relay coil fails then the corresponding relay Red LED goes on telling the user that the relay has failed, else the Green LED shows the relay ON/OFF status and signal from MASSO.
Quote from MASSO Support on February 26, 2020, 6:51 am
  1. Its a 6 relay unit.
  2. works on 24VDC.

What about a 12v version?



Just to add to this, I finally got around to wiring up my coolant relays. I have the 8 channel board that's available on Amazon for something like $0.37USD... It has active low inputs, which means that I need to connect ground to any input to trigger it. I had to add a separate 5V power supply for this relay board.

Masso doesn't work with it as-is.

What I found is that Masso actually outputs ~1.1V DC when the output is set low - NOT 0V as stated in the docs and as I understand TTL to work. If I tie the Masso TTL output low with a 4.7k resistor, and setup the output to be normally high, low when coolant is on, then all is well. FWIW, I started with a 10K resistor and it didn't pull the input low quite hard enough. I would NOT recommend going much lower than 4.7k.

I hope this helps.

- Mike

Quote from MASSO Support on February 22, 2020, 9:32 pm

Given that so many people have issues with all the non-standard and poor quality relay boards, we are releasing MASSO relay modules next month which will provide easy installation and we will also provide wiring examples. This way there won't be any confusion and we can standardize things with better quality products.

It's next month.  When will the Masso relay be available for sale?

the relay modules will be available on the website around 25th March.


That's great news Jatinder. Just ordered the sheetmetal parts for my new custom designed mill enclosure today.  I plan on setting it up with a new G3 in a couple weeks. Im so anxious to get my G3 up and running.  Will definitely need to order the new Masso relay module to go with it as well. Thanks for all your hard work and terrific support.

Cheers, Stephen Brown


Great to hear about the Relays being supplied, just looking at putting some in currently so will purchase.

There are a couple of questions I have, just in case I should still source 1 from elsewhere now though.

  • I have a G2 with the 7 relay outputs and I want to use pin 7 for an e-stop to open a 3.3 volt circuit to the e-stop on the lathe control card to stop the spindle. I'm gathering that the 6 relay module on offer can have each relay be configured to NC as well as NO?
  • I also gather that the relays are controlled via TTL output, but since I want to use pin 7 of the Relay Output of the G2 can the relays on offer still be used without a TTL signal.? I'm guessing no, since each relay would need an independent 24V coil supply(-ve at least anyway), but just checking. I guess I could just use a TTL output pin to do the job, but should I? The pin 7 Relay output is for e - stop yes?

Regards Sam.

Hi @sam

I suspect  that the new TTL relays will not work with the G2 relay outputs as they will be designed to operate with the TTL signal while the relay outputs are current sinks.

You cannot reasign the Estop relay output to a TTL output but you can simply connect a relay to relay output 7 on the G2 and it will operate when you release the Estop. The current limit of the relay output is 400mA but keep it well under that limit.

Cheers Peter