Kitamura MC-2 Fanuc 6Mb -- M20 THRU M23

[moldmker]

1981 Kitamura MC-2 Fanuc 6Mb

Here's what I want to do:

Hook up an external air solenoid to control air blast via program control.
I don't want to tap into the coolant circuit as I use the coolant on other tools.

Here's what I have:

There's a row of relays in the control cabinet, 4 of which are numbered M20 thru M23.
According to my manual, these are optional M functions.

If I issue M20 thru M23 in a program, the program locks up at that command and must be reset.

Watching the LEDs on the the relays, here's the results after entering the following M codes in MDI:
M20 -- nothing.
M21 -- m20 LED on.
M22 -- m21 LED on.
M23 -- m20 and m21 LED on.
(after issuing each m code, reset had to be pressed)

Can I get an explanation on how these M codes are to be used and are they for hooking up external devices?
Is there a parameter setting to make these work correctly?

I have ladder and address diagrams but need help interpreting them.

Thanks,
Bob

[Dan Fritz]

Your relays seem to represent the upper digit of the BCD output. Fanuc uses 8 outputs for M-codes, and they are labeled:

(lower digit)
M10
M11
M12
M13

Upper digit
M20
M21
M22
M23


The 2-digit M-code that you enter in MDI is sent as a BCD number. The first digit of the M-code is sent with the M10, M11, M12, and M13 relays like so:

M01 M10 on
M02 M11 on
M03 M10 and M11 on
M04 M12 on
M05 M12 and M10 on
M06 M12 and M11 on
M07 M12, M11, and M10 on
M08 M13 on
M09 M13 and M10 on

Now, for the second digit of the M-code:
M10 M20 on
M20 M21 on
M30 M20 and M21 on
M40 M22 on
M50 M22 and M20 on
M60 M22 and M21 on
M70 M22, M21, and M20 on
M80 M23 on
M90 M23 and M20 on

Now, when you program a 2-digit M-code like "M34", you get:

M21, M20, M12

When you program an "M57" you get:

M20, M22, M10, M11, and M12

Clear as mud, huh?

[Al_The_Man]

Originally Posted by moldmker (after issuing each m code, reset had to be pressed) Is there a parameter setting to make these work correctly? I have ladder and address diagrams but need help interpreting them. Thanks, Bob

Its a long time since I did anything on the 6m ladder, but if you can view the ladder you should be able to see the rung for that particular output and see what resets it.
When an M code is issued, the control has to see a Fin(ish) signal back, some M codes issue the Fin signal at once, like coolant on etc, where you don't need to wait for confirmation, But if your M codes are setting the relay on, that is the first step, but they hang, or wait for a Fin signal, that is why you have to push reset.
There may be one or more inputs that will trigger the Fin signal to allow the customisation you are looking for, you will have to study the inputs and outputs to be able to go any further, because obviously you would want to use another M code to reset the function.
Al.

[greyghost34]

Bob,

I agree with Al about the finish signal. We wanted to have a vac pump under program control so we had a friend of ours who is a EE design a box that had a 110v outlet, a connection to the control relay and a reset switch. Now we program an M20 or whatever and it turns on the 110v outlet, waits a predetermined amout of time and sends a finished signal back to the control. A second M20 turns the outlet off. The reset switch is useful if things get out of sequence. There are timing issues with the finish signal. Too soon and the control wont recognize it. I'm talking milliseconds here.
If you are interested I could ask my friend if he would be interested in building one for you and what the cost would be.

Ken

[moldmker]

I was in contact with Kitamura and they did indeed confirm that the M20 thru M23 codes need to see a finish signal from the device.

I've built M boxes for my other CNC but that didn't require any return signal.

It seems like this would've certainly been made many times before, is there a published schematic of what the timer and relay circuit would look like? (my web searches aren't turning up anything)

Ken, could you email me and maybe I can proceed with your guy?

Thanks for all the input.

Bob
rje@early.com