Linking multiple signals/pins together

Hi all.
Been stumbling around classic ladder learning the basics to add functions to my mill.
I have a question. How do you go about linking a pin to multiple signals or the inverse?
I have a spindle break button as a momentary switch on my control panel which I would like to turn on and off the spindle brake. I have been unsuccessful so far at the pin on the mesa card is already driven by another signal coming from HAL
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There must be a way to do this as plenty of people have physical buttons as well as buttons inside the gui.

Thanks in advance.
 

To expand on what Andy said:

If you want to influence a hal signal with multiple hal output pins, then you must use some kind of hal logic components, because only one hal output pin can be connected to any one signal name.

So for your example where I shall assume your spindle brake is already connected to the hal output pin "spindle.0.brake".  You will have to add a logic component.  If you want to say add a physical physical button to override your spindle brake.  If your config were a parallel port config with the spindle brake connected to pin 14 and the button to pin 12, your hall file might look something like this:


With the above, the spindle brake would be on only if both pins "spindle.0.brake" and "parport.0.pin-12-in-not" are true. If either one or both are false then the brake should be turned off.

First off all, Linuxcnc hal is a very powerful PLC language. You do not need classic ladder, python, c/c ++…
You can control a cnc machine using hal only  +  a dumb ui that can send and display hal signals such as pyvcp and/or hardwired panel.

To expand further on Andy and Todd explanations, and since this question about connecting hal signal confuses new hal users, I am adding block diagram to show how to connect hal signals (You can think of  hal signals as wire that connects hal components pins together).This block diagram for very simple example to show how to connect hal signals together. It has a push button input on the operator control panel and one pyvcp widget push button on the screen. If either push button is pushed the brake is energize and the pyvcp led on the screen lights up.From the diagram you notice that the two inputs from mesa 7i77 and pyvcp are not tied together but rather connected through a hal component in this case it’s an OR component. However, the output from the OR component is tied to two separate pins, Mesa digital output and pyvcp led widget.We can conclude that two separate hal input pins cannot be tied together and require a hal component. For outputs, two separate hal pins can be tied together. Of course, in both cases the signals data must be the same type. You cannot connect a floating-point signal with an S32 … Another important point regarding hal, you need to understand the difference between a hal pin name and hal signal name.

reference:
linuxcnc.org/docs/2.4/html/hal_basic_hal.html#r1_1_4 

netlisting for above diagram:
loadrt or2  count= 1
addf or2.0 servo-thread 
#           signal/wire                 Pins that are connected together
#===+===============+=========================================
net      turn-brake-on-pb       or2.0.in0  hm2-7i92.0.7i77.0.0.input-00                           
net      turn-brake-on-ui        pyvcp.di-00  or2.0.in1                                                     
net      brake-is-on                or2.0.out  hm2-7i92.0.7i77.0.0.output-00  pyvcp.do-00    



 

Thanks all
still a bit lost but the above answers a lot of questions.

currently my Hal looks like the below, i will keep using the spindle brake as it is a good example.

most of the below was created by the pncconf Wizard and i am using GMOCAPY


So would my new lines look something like
Then i have the additional complication of my brake button only being momentary but that might be where classic ladder comes in.

 

@Benb: Classic ladder is fantastic for seeing what is going on. I find it nice for experimenting.
If someone already is proficient with phython, I guess they will prefer that. I found it interesting that I could obviously integrate some phython script. (nice to know)

@walkahz

I am not sure if I understood the problem correct?

You have a physical button and not matter what you want to slamm the spindle brake in, when the button is pressed?



I am reasonably sure that you do not have to give up on classic ladder and it can be done!.

True ClassicLadder is not necessary.  Virtually any simple logic function that you might need can be performed in hal using logic components.  But if you are used to programming PLCs or for some very complicated logic it may be simpler to us CL.

If you'd prefer to do your logic within ClassicLadder instead of using an and2 component that would be fine as well, and would make sense if you are already bringing your button signal through CL  However I probably wouldn't bother adding CL to a config just to do a few ors and ands.  (That said I do like CL and am using it on at least one machine.)

To do that you would need to separate your existing spindle brake signal from the halpin for the brake's io on the Mesa card, then connect each to an input and output from CL.

Haha, OP is asking for a way to do it in classic ladder! (Me thinking why not ordering parts from a machine shop ? )

We can also hook up hmi or hal pins to the inputs and outputs of classic ladder. e.g.

To hook up one of the halui elements might be very easy, if you want to just replicate a (mouse klick button)

Greetings Timo
 

deleted, because editor messes everything up

Recent test:

7i95


The input-04 is just any that was not yet used in the *.hal.
The out-07 was as well one that was not yet used.

I can switch off the brake with the mouse on the Axis screen
 

As soon as the Input 4 on my mesa card gets activated, the %I4 is active and coil %Q7 is activated.
The %Q7 is linked with the halui and does the same as a checking the box on Axis screen with my mouse.
 


Greetings Timo