Even though your MPG jogwheel produces differential outputs via A+,A-,B+,B- you can use them as single ended outputs by ignoring the A-,B- outputs and just use the A+, B+. Eliminating the need for theDS3486.

Cheers,

Peter.

GaryDrew:
All the m5i20 inputs are essentially identical, so it doesn’t matter to which input number you wire a switch as long as your HAL configuration has that same number. Once the signal is in HAL it can then be wired whichever way you like to the motion-controller or other parts of EMC.

I don’t have a diagram for the selector switch. The 8-to-3-line decoder is used just to save pins, it could easily be left out of the design and the 6-pos selector switch would then use 6 input pins on the m5i20.

If you look at the datasheet:
http://focus.ti.com/docs/prod/folders/print/sn74hc148.html
there is a truth-table on p. 2 which should explain how it works. You pull any of the inputs low, and a corresponding bit-pattern will be output on the three output-pins. That is easily wired by having pull-up resistors on all the inputs, and then having the 6-pos switch ground one of inputs 0 to 5.

HTH,

Anders

Many thanks for listing the pendant info.
I did the 3d_chips.ngc gcode demo file thats in emc many years ago,and I am finally trying a emc based servo control with the mesa 5i20 / 7i33 / 7i37 over in the UK
I wandered which 5i20 inputs you used for the Pushbuttons: spindle on/off (yellow, m5i20.0.in-XX?), and program execution (red=pause m5i20.0.in-XX?, green=play/step m5i20.0.in-XX?) and if you have a diagram of the selector switch logic for the pendant.

Regards Gary

Now I see in the file where you are using “sets” and “linksp” to set the match pattern for the match8.x.bx.

Will the jog wheel function while in motion?

Thanks for the information.

EMC contains a software PLC, classicladder, which I’m sure could be for the functionality I want - I just haven’t had time to look at this for a while.

You have most of the idea right for my rotary switch HAL. The rotary switch has six positions which are encoded by the SN74HC148 into a three-bit value. In theory those three bits can be in eight different states, but as the switch only has six positions only six of those states are used.

I use a match8 block to detect which state we are in. The match8 block has two 8-bit inputs, and will output a true signal if those two 8-bit inputs are identical.

So for one function, say X-jog, I decide it’s going to be on when the 3-bit patter is for example 1-0-1. I then hard-wire constant 1s and 0s to one input of a match8 block, and the SN74HC148 to the other input. So now this particular match8 block will show a true output only when the rotary switch is in the 1-0-1 position.

There’s a corresponding match8 block for each of the other functions where the other 8-bit input is just hardwired to a different constant state 0-0-0, 0-0-1, and so on.

No BCD involved, just raw matching of bit-patterns. The output of the match8 block is then used as an enable for jogging etc.

Anders

I do a lot of PLC programming and in that world I would use the logic
Button On if output is off latch it on else if output is on latch it off. Don’t know if this helps in any way with your coolant issue. Is the input being reevaluated some how at certain intervals?

Trying hard to understand your jog.hal file. Your using the pins m5i20.0.in-00, 01, 02 as your selection inputs which gives you eight possible combinations. The match8 sections for each axis is the same except for the match8.x. How does HAL make a match based on the inputs? Is it converting the inputs to BCD?

Thanks for the information on the pendant control.
John

HAL is very much like building real electronics, so a degree in electrical engineering can’t hurt

There should be some tutorial with siggen and halscope in the manual, did you go through that? Also learn to use halmeter.

Jeff Epler recently worked on visualizing a HAL circuit. That might help you see how everything is connected:
http://axis.unpythonic.net/01174426278

pyVCP should be ideal for learning to build easy HAL circuits and testing them. Maybe someone should make a set of tutorials using pyVCP and HAL?

Anders

Williams

My reply:
Hi Manfredi,

The benefit with a purpose-made joghweel is that it has detents, i.e. it will stay at the position you leave it. A normal rotary encoder would work, but it would not be as nice to use.

A quick-and-dirty way of using differential encoder signals is to just use the +A and +B signals (leave the -A and -B signals unconnected).
If you really want the added noise immunity offered by differential signals then you need the DS3486 circuit or something similar.

The circuit I am using is from an IRF datasheet/application note.
http://www.irf.com/technical-info/refdesigns/dg-irmck201.pdf
see the next to last page.

Anders