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The Ultimate Guide to Touch Probe and Tool Height Setter Configuration on Acorn, CNC12 v4.12
(Guide Version: 1.0)

UPDATE 3/18/2019:This guide does not apply for CNC12 Version 4.14 and higher. All of the issues reported here have been fixed in version 4.14. If you are still running Version 4.12 and are having issues with probe setup, I highly recommend to upgrade to the latest version of Acorn CNC12 now. here is link. https://www.centroidcnc.com/centroid_di ... loads.html

and Follow this Probe Setup Guide

UPDATE 9/29/2018: An issue has been found that impacts MDI functionality with removable Touch Probes with Input Type NC. If a TP with Input Type NC is being disconnected, all G=Move commands (e.g G28) executed from the MDI are causing Error 916. It looks like the MDI is always checking the input configured in parameter 11 for a trip signal. When the TP is being removed, that signal will open which is the same status as a trip signal. This issue is currently being investigated and the guide will be updated if a solutions is being found. If somebody has a solution for this, please post it below.

I’m the proud owner of an Acorn Board with CNC12 control software. I think the Acorn Board is a fantastic solution and was very easy to install and configure up to the point when I tried to configure both, a Touch Probe and a Tool Touch-Off Plate on my system. If you have tried that too, you might have encountered that this can be a challenging process because there are some glitches in the CNCWizard and the CNC12 software when using non Centroid probes that will not always give you the expected results. This guide is intended to make probe configuration on Acorn an easy and straightforward process.

Disclaimer: USE THIS GUIDE ON YOUR OWN RISK!
I am not affiliated with Centroid in any way and I do not have access to the source code of CNCWizard and CNC12. My findings are based on extensive testing and reverse engineering to find out the relationship between the Input configurations done in CNCWizard, the parameter settings that the Wizard generates and the behavior of CNC12 with these parameters. My findings are based on CNC12 Version 4.12. Based on my tests, the following guide should get any combination of Touch Probe and Tool Height Setter working with Acorn and CNC12. My tests were focused on verifying that the probing cycles are working with the correct trip signals and if the configuration has any impact on jogging and spindle lock. This guide has not been certified by Centroid and I cannot give any guarantees that all combinations will work 100% for you.

Definitions
Trough out the guide I will use the following abbreviations:

TP = Touch Probe used to set work coordinates etc.
TT = Tool Touch-Off Plate used to set Z-Reference / Tool Height Offsets
NO = Normally Open is used for the type of probes that have an open Input when NOT tripped
NC = Normally Closed is used for the type of probes that have a closed Input when NOT tripped
Fixed = Hardwired probe connection. This also includes probes with a plug that will be left connected permanently
Removable = A probe that will be connected for probing and removed after probing is completed

Input/Output Map in CNC12 (Alt i)
To help with troubleshooting Input/Output problems, the Input/Output Map in CNC12 is a good place to start and can be accessed by pressing Alt i on the main menu of CNC12 and it will look like this:


It is important to understand the meaning of the colors of the LEDs. The Acorn has a total of 8 Inputs that can be seen on the left of the first row of the Map screen. If an Input is configured in the Wizard as NO, the LED for that Input will have a line on top of it (look at Input 7 in the picture as an example). No line above the LED indicates the Input has been specified as NC in the Wizard. This is true even for Inputs that have been configured as “Unused”. By default an “Unused” Input is configured as NC but when you change that to NO, a line above the LED will show up.

So what do the colors mean? There seems to be a misperception that Green means Input is closed and Red means Input is open. That is NOT the case. A LED shows Green when the signal on that Input matches the setting for that Input in the Wizard. So if an Input has been configured as NO and there’s no signal on that Input (Input is Open), the light will show Green and will turn Red when the Input closes. For an Input that has been set to NC, the light will be Green when the Input is closed (Input pulled to Ground) and turn Red when the Input opens.

If you have already configured probes on your system, check the color of the LED of your probe Input. If the color is Red when the probe is NOT tripped, you have configured the opposite Input Type of what your probe really is. The good thing is your probe might still work correctly as long as your parameters do have a matching, inversed Input value. The problem is that the rules for inversion are inconsistent with certain parameters.

So when you follow the Guide, pay close attention if an Input value of a parameter is positive or negative. If you follow the Guide to the T, you should get a Green light for your probe Input LED when the probe is not tripped. The settings might not always make logical sense but they should work.

Warning
IMPORTANT CNCWizard is overwriting the parameters every time you save a configuration file. If you are making manual parameter changes in CNC12 and run the Wizard after making these changes, there is a good chance the Wizard will overwrite your changes again and will leave your probes in a non-working state. So avoid using the Wizard after making manual changes. If you have to use the Wizard again for some reasons, make sure you re-configure these parameters again when you re-start CNC12.

How to use the Guide

Step 1

There are two tables, one for the TP and one for the TT. Start each table in the left column, answer the question in the heading of the column and pick the row that matches your situation. Work your way to the right until you get to the columns that give you the settings for the CNCWizard and CNC12 for your configuration.

I suggest that you download and print out the configuration tables below and mark the recommended settings for the TP and the TT (if you have both) before you go to Step 2. In the “Comments” column there are reference letters and numbers that point to the corresponding Comments below the configuration tables that are relevant to your configuration and will give warnings or additional information why these settings were chosen. When you have determined all the CNCWizard and CNC12 parameter settings for your probes, go to Step2.



Step 2
Start CNCWizard and configure all Inputs with the recommended settings from the Guide. Save the configuration and exit CNCWizard.

Step 3
Start CNC12 and press Alt i to get to the Input/Output Map. Verify that the LEDs of your probes are Green when connected and NOT tripped. The LED should turn Red when tripped. If this is not the case, you have selected the wrong Input Type in CNCWizard for your probe (or something might be wrong with your wiring). Go back to Step 1 and follow the Guide using the opposite Input Type.

If your LEDs work correctly, go to the Parameter Configuration page by selecting Setup [F1] -> Config [F3] -> Parms [F3] from the Main Screen of CNC12 (you might need to press the ESC key until you reach the Main Screen). If you have Password enabled, you will be prompted for a Password. The default Password is 137. Change all the Parameters to the recommended values from the Guide. Save the changed Parameters by pressing Save [F10].

Step 4
Test your configuration and verify that the probing cycles in CNC12 can be started and are recognizing the trip signal. Be aware of the following:

• The availability of probing cycles depends on the version of CNC12 you have (Free, Pro or Digitizing Bundle). Check Centroid’s website for more information what’s available for your version.

• On the Setup [ F1] -> Tool [F2] -> Offset Lib. [F1] screen the “Z-Ref [F1]” function only works if Parameter 43 has been configured to use the TT to set the Z-Reference. For details about Parameter 43 see Step 5.

• On the Setup [ F1] -> Tool [F2] -> Offset Lib. [F1] screen the “Auto Measure [F3] functions does look at different parameters than the “Z-Ref” function. That means that the “Z-Ref” function might work but the “Auto Measure” function doesn’t.

I recommend not mounting the probes onto your machine for the tests. Leave them somewhere safe and create a trip signal with your hands. Make sure your machine is in a safe position before you start a probing cycle so it doesn’t crash into something should a probing cycle not react to the trip signal. Use the RESET-Button to stop a probing cycle that’s ignoring the trip signal from the probe.

Step 5
This Guide focuses on the settings required in CNCWizard and CNC12 to get a probe recognized and force CNC12 to look at the correct Input for a trip signal during a probing cycle. Below is a description of the main parameters related to probing. The values of the parameter numbers in RED should match the values from the Guide Tables. Do not change these values unless you know exactly what you are doing. Check the other parameters if they match your requirements and change them if needed. If you have configured CNC12 to use Inches, the feed parameters are in inches/min and distance parameters in inches. For Metric configuration, feed parameters are in mm/min and distance parameters in mm.

I also recommend checking Centroid’s documentation about more details of these parameters.

• Parameter 11 : Input Number of the TP. If you have only a TT or you have a removable TP and TT that are sharing the same Input, enter the same Input Number into Parameter 11 & 44. Default value is 0.

• Parameter 12 : Tool Number of the TP. This number must reflect the position of your TP in the Tool Library. Default value is 0.

• Parameter 13 : Recovery Distance for TP. This is the distance the TP moves off of a surface after a trip signal has been received before attempting to traverse parallel to the surface. The default value is 0.05” or 1.27mm.

• Parameter 14 : Fast Probing Rate for TP and TT. This speed is used for initial surface detection. The default value is 10ipm, 254mm/min.

• Parameter 15 : Slow Probing Rate for TP and TT. This is the speed used for the final measuring move and is a tradeoff between speed and accuracy. The default setting is 1ipm, 25.4mm/min.

• Parameter 16 : Maximum Probing Distance for TP and TT. This is the maximum distance a probing cycle “searches” for a surface in a given direction if no travel limits have been entered. The default is 10”, 254mm. This might need to be increased if very large features are measured.

• Parameter 17 : Detector Location Return Point for TT. The values of this parameter can be as follows:
  • 0 = The tool measurement will take place at the current X and Y position (Default Value)
  • 1 = Use X and Y position configured in G28 (same as G30 P1)
  • 2 = Use X and Y position configured in G30 (same as G30 P2)
  • 3 = Use X and Y position configured in G30 P3
  • 4 = Use X and Y position configured in G30 P4

• Parameter 18 : PLC Input Spindle Inhibitor for TP. This parameter should supposedly be configured with the Input Number for the “ProbeDetect” signal of the TP. My findings are that this parameter can be 0 and ProbeDetect still works as long as the Detect Input Signal matches the configured Type NO or NC. If an Input Value is being entered in parameter 18, it always needs to be a positive number, no matter if the Detect Signal is NO or NC. If a negative value is entered, the probing cycle will give a "Probe not detected" error. Default value is 0.

• Parameter 43 : Automatic Tool Measurement Options for TT. This is a binary parameter that allows 3 separate settings been configured in one parameter. This parameter should have been configured correctly by the Wizard based on the information you provided in the “Tool Touch Off Options” pop-up window when you selected “ToolTouchOff” for an Input.
  
  This is how the parameter is configured (just add up the number for every option you need):
  • The default value is 0
  • Add 1 if you want the Height of the TT been subtracted from the measurement. The height of the TT is configured in parameter 71
  • Add 2 to use the TT for setting the Z-Reference. The “Z-Ref [F1]” function will not work without this
  • Add 4 if you want a Warning Message to attach the TT before probing.

• Parameter 44 : Input Number of the TT. See Comment 5) for additional information

• Parameter 71 : The Height value of the TT. Configure also parameter 43 if you want this height value of the TT be subtracted from the Tool Height Measurement. Default value is 0.

• Parameter 155: Centroid DSP Probe installed. Unless you have a Centroid DSP probe, this value needs to be 0, which is the default value.

• Parameter 257 : Input Number of the Detect Input of the TT. IMPORTANT! This parameter plays a major role in getting a TT working properly. If this parameter is 0, which is the default value, the probing function Setup [ F1] -> Tool [F2] -> Offset Lib. [F1] ->“Auto Measure [F3] will look for a trip signal on the Input configured in parameter 11 instead of parameter 44. If you have a TT without a Detect Input, you need to fake a signal in parameter 257 in order to get the “Auto Measure” function to accept a trip signal from the TT and not the TP. This can be achieved by entering the positive value of the TT Input in this parameter. You will get the right settings if you follow the Guide.

If you reached this point and followed the Guide to the T, you should hopefully have a machine with working TP and TT. If you have a working configuration, create a report.zip file so you can restore your settings in the case the Wizard will overwrite your settings again.
If the provided settings don’t work for your configuration, if you find any mistakes or have suggestions to make the Guide better, please report it in this thread.

Below is more information about the issues I have found using Wizard Settings. This information might help you troubleshooting your configuration settings should the Guide fail you.

 
CNCWizard Input Settings related to Probing

This list describes all the probe related Input PLC Names available in CNCWizard, what they are supposed to do and my findings:

• ProbeTripped : This is used to configure the Input of the TP. Instructions say to configure the Input Type with the signal your TP has when tripped. So in theory this should be set to NO for a TP that is really NC and to NC if the TP is in fact NO. There might be some history behind it that this has been implemented this way but it’s very confusing and not really necessary. It will also give you inverted LED colors in the Input/Output Map.
  
  Be aware that when you configure an Input as “ProbeTripped” with Input Type NO or NC, CNC12 will prevent Fast Jog to protect your probe if the signal on the probe Input matches the configured Input Type setting from the Wizard. So if you have configured the Input as NC and the Input is closed, or the Input Type is configured NO and the Input is open, you can’t switch to Fast Jog until that signal reverses. This is of course a problem for hard-wired probes, as the signal will always match when the TP is not tripped and will never allow you to Fast Jog your machine anymore. It’s also a problem for removable probes with Input Type NO because CNC12 cannot see a difference between an open signal from a working probe or an open signal from a disconnected probe. To get around this issue, you need to configure your TP Input as “Unused” instead of “ProbeTripped”. See Comment 4) for side effects.

• ProbeDetect : This is used to configure the Input of the Acorn that has the Detect Signal of the TP wired to it. The Input Type can be configured as NO or NC and CNC12 will prevent the spindle from spinning when the signal on this Input matches the Input Type. This Input can be shared with a TT if your TT doesn’t require your spindle to spin. Note that the Wizard currently has no PLC Name for a TT Detect Signal. If you need a second Detect Input for your TT or if you need a Detect Input that lets your spindle spin, configure the Input as “Unused” with the correct Input Type NO or NC as required.

• ToolTouchOff : This is used configure the Input of the TT. As soon as you select this PLC Name for an Input, the Wizard will pop-up a “Tool Touch-Off Options” window where you can specify several options for the TT. These options will configure the following parameters:
  • 14 : Fast Probing Rate (value shared with TP, inches/min or mm/min depending on your machine settings)
  • 15 : Slow Probing Rate (value shared with TP, inches/min or mm/min depending on your machine settings)
  • 16 : Max Probing Distance (value shared with TP, inches or mm depending on your machine settings)
  • 43 : Automatic Tool Measurement Options (see Parameter Table above what the number means)
  • 71 : Height of Tool Touch-Off , inches or mm depending on your machine settings)
  WARNING! If you use ToolTouchOff together with an Input configured as “ProbeTripped”, the Wizard will overwrite the TP Parameter 11 with the Input Number of the TT and disables your TP. This will happen every time you save a new configuration in the Wizard.

• Unused : Configure an Input as Unused if you want to get around the restrictions of a specific PLC Name as described above

 
Other Considerations

Safeguard your Probe with a Detect Input
If you are using removable probes, I highly recommend using a Detect Input. If both of your probes, TP and TT are the same Input Type, you can share the Probe Input as well as the Detect Input between the probes. Just follow the Guide using the same Probe and Detect Input for both probes.

Usually the Plug and Connector of a probe have a lot of unused pins. On the connector side just wire one spare pin to a Detect Input and a second spare pin to COM on the Acorn board. On the Plug side of the probe, just shorten the matching two pins and your probe has a Detect function with Input Type NC.

For hard-wired TPs there is no good automated way to prevent your spindle from spinning. You should make it a habit to lock the spindle (or turn off power to the spindle if there’s an option) when you mount the TP and unlock when you remove it. If you have no spindle lock or power switch, you can consider installing an On/Off Spindle Lock switch on your control box that you wire as a “ProbeDetect" Input on your Acorn board. You could also use one of the AUX keys for this function.

Saving Inputs
If you are short on Inputs and both of your probes, TP and TT, have the same Input Type, you can consider using the same Input for both probes.

If both probes are hard-wired and the same Input Type, you can wire them to the same Input as follows:

- Input Type NO: Wire them parallel to the same Input
- Input Type NC: Wire them in series to the same Input

If both TP and TT are removable and have the same Input Type, you can use the same Input for both probes (see also “Safeguard your Probe with a Detect Signal” above).

If you use any of these options, follow the Guide by using the same Input Number for both probes and you should get working settings for this type of configuration.

Please post below your probe details if the guide did or didn't work for you.

-swissi

Good write up, I'm sure I will use it when I set up a touch probe. Andy

andyolney wrote: ↑Wed Sep 26, 2018 5:17 pm Good write up, I'm sure I will use it when I set up a touch probe. Andy

I appreciate the effort that ANY users goes through to detail this sort of specific topic.
It might not be 100% accurate, BUT its a good start, and those of us that use the info, find something to improve the topic can add to it, and make it as good as it can be. Flesh it out together.

The next software revision will make it easier to setup probes and this might have to be revised OR completely rewritten, but until then, its a good starting point. Thank you again for taking the time to post it Swissi. Please edit and update as you run across changes/improvements.

Marty

Thanks Marty.

The purpose of this guide is to have one repository in the forum of all currently know issues regarding probing setup and functionality to help new users to workaround these issues and support Centroid to fix them in the next release. I hope no more such guide will be necessary in the next release

Version 1.0 of the guide is based on the findings of my testings. My tests were limited to the following checks:

• Does the probe recognize the trip signal from the correct input in the Part Setup and Tool Height Offset Screen

• Does the Spindle Inhibitor work

• Does the Fast Jog Inhibitor work correctly

• If a Detect Input is being used, is it recognized properly and does it have any side effects

As additional issues and solutions are reported or mistakes are pointed out, I'll update the guide accordingly.

At the moment there's a known issue with MDI functionality with a removable Touch Probe with Input Type NC that has no solution. If the Touch Probe is not attached, all G-Moves (e.g. G28, G30 etc) are causing Error 916 when executed from the MDI. If somebody has a solution of how to prevent this error, please post a Reply.

-swissi

The error 916 message means that the axis traveled the maximum allowable distance, which is set via parameter 16, without ever seeing a trip. That means that they need to increase the value of that parameter. Thanks.

Error 916 is "Unexpected probe contact", "probed tripped when a cycle did not expected contact".

What you are referring to is Error 918 "Probe unable to detect surface", "Probe travelled maximum distance without contact, dsp window checking failed, or probe repeatability failed."

This problem is very easy to reproduce. Just disconnect a working Touch Probe of Input Type NC, start the MDI and try to execute a G28. You will get an instant Error 916 without any travel at all.

-swissi

swissi wrote: ↑Tue Oct 02, 2018 10:01 am Error 916 is "Unexpected probe contact", "probed tripped when a cycle did not expected contact".

What you are referring to is Error 918 "Probe unable to detect surface", "Probe travelled maximum distance without contact, dsp window checking failed, or probe repeatability failed."

This problem is very easy to reproduce. Just disconnect a working Touch Probe of Input Type NC, start the MDI and try to execute a G28. You will get an instant Error 916 without any travel at all.

-swissi

I certainly would not be correcting Centroid Swissi...you made a reference in your document to Error 916 not 918. Keith is trying to explain the error. If there is confusion of terminology, then its best clarified. (I'm guilty of that more often than not)

I welcome Centroid proofing your document. Its the only way to make it as accurate is it can be. Otherwise it is your interpretation which may not be accurate. I wished I could add more to it but I have not much experience as of yet with probes.

Marty

Centroid Alarm 916 Unexpected probe contact
Cause & Effect
probed tripped when a cycle did not expected contact
Centroid Alarm 916 Unexpected probe contact

Centroid Alarm 918 Probe unable to detect surface
Cause & Effect
Probe travelled maximum distance without contact, dsp window checking failed, or probe repeatability failed.
Centroid Alarm 918 Probe unable to detect surface

I used swissi's guide, and had some discussions with him. I get the 916 error. Attached a fresh report.

I use a NO TT and a NC TP.

I start the machine (probe disconnected), I home the machine, I press F3 (MDI), when I type G28 or G30 P4 (to go to my tool change position) and cycle start, I get error 916 probe tripped.

I also just noticed: when I type G28 and a space, or G30 and a space I immediately see in Red 'Feed Hold' under the line 'Spindle', even before pressing enter and cycle start.

Here is the issue. Parameter 11 is set to a negative value which is telling the control that when the ProbeTripped signal is open, that it's being tripped. Since you have disconnected the probe from the system, the control believes that it's always tripped which is why you are getting that 916 message.

There are issues with the probe setup in the v4.12 Wizard for some combinations and we are currently working through to resolve for the upcoming release of cnc12 v4.1x+.. so for now.. simply use the CNC12 setup configuration parameters...here is the work around!
please do the following.

Probe setup Instructions for CNC12 v4.12

1.) Set the Acorn Wizard Input Types for “ProbeTripped”, “ProbeDetect”, and “Tool TouchOff” to “NC” whether you are using an NC or NO type of device. then “Write Settings to CNC control”.

2.) Press <ALT i> (both the “ALT” and the “i” key at the same time) from the main CNC12 screen which brings up the PLC Diagnostic menu. You will see 4 rows of red and green dots. The top row on the left are the Acorn inputs. ( you can use the arrow keys to move the cursor on top of the input LED to identify that input assignment. Notice the name of the input is displayed at the bottom of the screen, this lets you know what that particular input purpose is and what input label has been assigned to that input in the Wizard.)

3.) Connect the Probes and observe the color of the input “LED”s to see what state the LED is in when the probe(s) are not tripped.

4.) Now, observe the color of the input “LED” to see what state the LED is in when the device is tripped.

a.) If the LED is normally red and then turns green when tripped (or when connected for detect signal), then the CNC12 probe parameter values must be positive values.

b.) If the LED is normally green and then turns red when tripped (or when connected for detect signal), then the CNC12 probe parameters values must be negative values.

5.) Once the Probe behavior has been identified in step 4, in CNC12 press F1(Setup)->F3(Config)->F3(Params) and correctly set the values of parameter numbers for Parameters: 11, 18, and 44.

Example #1, The ProbeTripped signal is set on input 7, the ToolTouchOff signal is also wired into input 7, and the is no ProbeDetect signal being used. So we set parameter 11 (TP input) to 50007, parameter 18=0 (no TP detect circuit), 257=0 (no TT detect circuit) and parameter 44 is set to 50007. (All these are positive values since the LED turns Green when the probes are tripped and the detect signal is plugged in.) Both probes have to the same type (NC or NO)

Example #2 Using a Centroid DP-4 Touch Probe and Centroid TT-1 Tool Touch Off Probe with the Detect Circuit.
With the Wizard set the the “ProbeTripped” input signal on input 7, the “Tool TouchOff” signal on input 7, and the “ProbeDetect” signal is on input 6. So we set parameter 11 to 50007, parameter 18 is set to 50006, parameter 44 is set to 50007 and P257=0


Having these parameters set correctly will make your probe and tool touch-off devices function correctly with the Centroid control. Since ACORN users are limited in the I/O that they have, you can use the same input for the tool touch-off device as well as when the probe is tripped as long as both the tool touch-off device and probe tripped signals are the same type of input as far as NO or NC. It has been done on Centroid controls with Centroid's probe and tool touch-off device for years. If you are using a detect signal for each device, they must use separate inputs because if not, the control will display a message stating that both devices are installed and it will not allow you to run that cycle. With that being said, there is a minor bug in the CNC12 software that when you are using Centroid's automatic tool height measurement software, it's looking at the input that is set in parameter 11 rather than parameter 44 and that issue will be resolved shortly. If the ProbeTripped and ToolTouchOff inputs are the same input, this will not be an issue.

Also, the SPACEBAR is a keyboard shortcut key which places the system in a Feed Hold state so when you are pressing the SPACEBAR when typing in the MDI block, you are placing the system in Feed Hold. That's not an issue because you need to press Cycle Start in order to run that code.

i made the attached PDF to help clear up any misunderstandings on what exactly a NC probe is vs a NO probe..

edit.. and i added visual representation of the Input LED state for the two different probe types when they are set up properly using the contained setup instructions.