LED circuit to monitor status of I/O & Motors on Acorn Board

[EricMack]

LED circuit to monitor status of I/O & Motors on Acorn Board

I visited a friends shop recently and his industrial Router control panels had LEDS for motor activity and direction for each axis as well as all I/O and spindle status. This was interesting and helpful - if not eye-catching - to be able to see at a glance what the controller was doing.

Ideally, I would like to mount LEDs on my control box to show status at a glance of various input and output signals on the Acorn - similar to the Rev 4 board but mounted on a PC Board in my control box. (See photo below)

I wonder who here may have already done something like this?

Can anyone suggest an appropriate LED Circuit to monitor an input or output signal that would not interfere with the Acorn operation in any way?


As an example, when I used Mach3, I had purchased a PMDX-179 board https://www.pmdx.com/PMDX-179 that did just this. It found it quite helpful.

PMDX-179 LED Panel

The signals I would like to monitor include:
- Inputs
- Outputs
- Motors enabled, direction, and active (steps)
- Probe/touch status (*comes from the Inputs side above)
- Spindle Active - would come from monitoring the 0-10VDC

[Richards]

What you want to do is actually quite complex. As I see it, you would need to sample each signal using a high-resistance/high-impedance input buffer so that you wouldn't interfere with the Acorn's signal. You would need to use pulse stretchers so that short pulses would last long enough to see visually. Because of the Relay Outputs on the V4 board, you could probably put a sensor circuit in parallel with whatever the relay is driving. The sensor would need to be the same voltage as the driven circuit. Step, direction, and enable signals from the DB25 or H2-H3 headers shouldn't be expected to drive a 2nd input. That's where you need a buffer circuit that basically draws nothing from the signal.

Years ago, I built a 48 LED status board as part of a Kodak-S printer controller. That status board used several microprocessors to handle the various machine states of the Kodak printer. It cost a lot to design, to build and to install. Today with $5 Arduinos on E-Bay, if you buffer the inputs properly so that you don't degrade the signals, the cost would be a minor factor but you would have to write the code. An inexpensive PLC could be used, but the PLCs that I use draw about 10mA per input, so you would still need to build a buffer board to protect the Acorn. Also, on a PLC, the scan rate could cause you to miss some signals.

[EricMack]

Thank you, Mike. I had a feeling that what I wanted to do was not quite as simple as it appeared -- which is why I began by doing some research and asking questions. Perhaps I'll just find a way to get a Rev 4 board and mount in a cabinet in a way that I can see it. It's not a huge deal beyond learning and testing. Thank you again.

[carbuthn]

Eric,

I originally wanted indicator lights, but after thinking about it I decided that I wouldn't be runninging the Acorn without the CNCPC and monitor.

The monitor displays the inputs, outputs, position and alarms. I can also see the status of my PLC.

I am happy with the information that I have,
Chuck

[cnckeith]

most of them are pretty easy to do....
but like chuck says.. spend some time running CNC12 then you may want something just a bit different.
THe Acorn board itself has LED's on it to indicated all of these items, great for initial hookup and commissioning.. and usually not used at all after that as its not necessary as CNC12 itself has messages and indicators on the screen and you can even create your own if you need more or different ones than what comes with CNC12 stock.