Content Preview
TB270 rev15 – Solving CNCPC to MPU Communication Errors
Centroid CNC controls communicate with the CNCPC via Ethernet connection This communication
method is very reliable and fast Setup and Installation details are critical for good reliable CNC
control performance These details are simple and easy to get right and should not be overlooked
Causes of CNC control to CNCPC communication errors fall into two main categories
1 PC related Windows settings firewall anti virus Ethernet adapters and related drivers Follow
PC Setup Guidance in Tech Bulletin #309
2 Use a Shielded Ethernet Cable
Common mistakes that cause CNC to PC Ethernet communication issues
1 Not using the Centroid CNC PC Tuner app to set up your system for CNC use Centroid CNC PC
Tuner App Youtube
Download PC Tuner App here
2 Not performing the Centroid CNC controller communications Bench Test
Communications Bench Test Youtube
3 Using a non shielded RJ45 a bulkhead connector
4 Using a non shielded Ethernet cable
5 Using a USB Ethernet adapter
6 Ethernet adapter drivers on the CNC PC haven't been updated always use manufacture drivers
when possible
7 ANY type of anti virus software installed you can't just simply turn it off you have to uninstall it
8 Windows firewall is blocking cncm exe cncr exe or cnct exe run the PC Tuner it will make the
exception for you
9 Windows or Laptop bios power saving feature turning off the Ethernet adapter Windows resetting
the ip address automatically run the PC Tuner it will make the settings for you
10 Other network devices attached/installed on the CNCPC run the PC Tuner it will make the
settings
11 The shielded Ethernet cable is bad try another shielded cable as a test
12 Wireless network on the CNCPC searching for connections
13 Windows Updates or any other auto updaters are active hogging up PC resources
Technical bulletins\TB270\TB270 Solving CNCPC to MPU Communication Errors Rev15 odt 1 2 26
TB270 rev15 – Solving CNCPC to MPU Communication Errors
14 Using the dedicated DC logic power supply for the Centroid CNC controller card Acorn
AcornSix Hickory Oak Allin1DC MPU11 to power other components
15 If using a Centroid supplied Mini CNCPC with multiple Ethernet Ports make sure the Ethernet
Cable to the Control is plugged into the Ethernet Port labeled “CNC”
Solve CNC control to CNCPC communication errors by getting these details right
1 Setup Windows for CNC control use Be sure to follow the details on how to properly setup
Windows 10/11 for use with a CNC control Settings that control sleep and Ethernet ip address
settings along with others settings are critical for good CNC control operation
Centroid’s CNC PC Tuner App automatically checks the system to meet hardware requirements and
configures everything needed for CNC use The Tuner App replaces Tech Bulletin 309 Centroid
CNC12 Windows 10/11 Configuration as it performs all of the TB’s tasks in one automated function
Centroid CNC PC Tuner App Youtube
Download PC Tuner App here
Technical bulletins\TB270\TB270 Solving CNCPC to MPU Communication Errors Rev15 odt 1 2 26
TB270 rev15 – Solving CNCPC to MPU Communication Errors
The most common cause of PC Data Receive Errors are firewalls and anti virus programs These
programs intercept and delay the real time data exchange between the CNC Control and the
CNCPC These delays can accumulate to the point that it triggers this fault If you are seeing PC Data
Receive Errors completely disable all firewalls and uninstall all anti virus programs Remove any Anti
Virus software* you can't just simply turn it off it must be uninstalled
If the Windows Firewall is ON the first time you run CNC12 the Windows firewall will typically ask
you to “allow” CNC12 to run be sure to check both the Public and Private check boxes when asked If
for some reason Windows doesn’t ask or you would simply like to check the Windows Firewall
permission status of CNC12 navigate to Windows Firewall Advanced settings panel and make sure
cncm/t/r/p is set to Private Public Enabled and Allow
Technical bulletins\TB270\TB270 Solving CNCPC to MPU Communication Errors Rev15 odt 1 2 26
TB270 rev15 – Solving CNCPC to MPU Communication Errors
A good firewall test is to simply disable the entire Windows firewall temporarily
2 Connect the Centroid CNC control board directly to the CNCPC Ethernet port with a Shielded
cable Do not use an RJ45 bulkhead connector* or a regular non shielded cable or a USB Ethernet
adapter or any other type of adapter We have seen a few bad Ethernet cables so its always a good
idea to have a spare shielded cable to test with as well
3 Run Windows Update and be sure to install the latest Ethernet adapter drivers directly from the
manufacturer’s website
4 Windows or Laptop* bios power saving feature is turning off the Ethernet adapter and/or
Windows resetting the IP address automatically Deselect “Obtain an IP address automatically” in
Windows Ethernet adapter settings and select “Use the following IP address”
5 Remove any other network devices* from the CNCPC Network traffic from other network devices
can cause a dramatic decrease in PC and network performance Remove all other network devices
and connections to the PC uninstall any hardware drivers or network utilities associated with network
hardware not associated with the network adapter connected to the CNC controller Wireless network
Technical bulletins\TB270\TB270 Solving CNCPC to MPU Communication Errors Rev15 odt 1 2 26
TB270 rev15 – Solving CNCPC to MPU Communication Errors
devices that are searching for a connection can be extremely resource intensive and interfere with
CNCPC to CNC control communication
6 Other applications running on the CNCPC The minimum hardware requirements specified by
Centroid take into account running only the CNC12 software If receiving PC Data Receive Errors
please terminate any other programs that may be running hogging up the PC resources
7 Windows anti virus 3 rd
party programs auto updaters can bring a PC to it's knees while checking
for downloading and/or installing updates Turn off automatic updates for Windows and other
applications that may hog system resources
8 Speed & Duplex Ethernet connection settings have shown to solve communication errors in some
cases This should be the last method attempted to solve PC related communication errors as its
repeatability is inconsistent
• Open Device Manager
• Find the Ethernet connection under “Network adapters ” Right click and select “Properties”
• Select the “Advanced” tab and scroll down the “Property” box to find “Speed & Duplex ”
• Change the Value to 1 of these 3 settings “100 Mbps Full Duplex ” “100 Mbps Half Duplex ” or
“Auto Negotiate ” click OK and run the communication stress test listed below on
“Discussions” page If problems persist change to a different setting and run the stress test
again
• If this does not solve the communication issues it’s recommended to leave this setting on “Auto
Negotiate ”
Technical bulletins\TB270\TB270 Solving CNCPC to MPU Communication Errors Rev15 odt 1 2 26
TB270 rev15 – Solving CNCPC to MPU Communication Errors
CNC system noise related communication errors Cables routing missing quench arcs aka
snubbers
1 Run the shielded Ethernet communications cable directly from the Centroid controller card to the
CNCPC The cable running between the MPU and CNCPC should be a single shielded cable that
does not connect to any switches hubs or butt connectors* Any of these things can effectively defeat
the shielding and introduce noise They may also likely introduce propagation delays which will cause
this error as well
2 Do not run the shielded Ethernet cable next to any three phase or power cables The Ethernet
cable should never be run alongside any three phase or other power cables Route the Ethernet
cable well away from spindle and servo motors and any other cables with inductive loads such as
coolant and lube pumps and especially solenoids and their related cables
3 All the inductive loads in the cnc system are required to have Quench Arcs aka snubbers
installed on them Quench arcs are very important and must be installed across the coils of all relays
solenoids and motors Quench arcs should be installed as close as physically possible to the load
coil itself See TB206 Noise Suppression
4 Use a CNCPC that at least meets the Centroid minimum CNCPC hardware specs Found here on
this page https //www centroidcnc com/centroid_diy/acorn_quick_start_guide html
Do Not use PC’s with Mobile Processors
Do Not use Windows Tablets
Do Not use Raspberry Pi’s or other computer on a chip “PCs”
Do use a CPU with a single core benchmark performance rating above 1500 this does not mean
you have to use a single core CPU which is impossible to find these days anyways The single core
bench mark rating of 1500 or higher is the performance rating is for ONE of the cores of the PC’s
CPU NOT the overall score combined core performance Check a CPU’s single core performance
rating here
https //www cpubenchmark net/singleThread html
It is cheap and easy these days to find a PC that exceeds the minimum Centroid Hardware
requirements so there is no savings in trying to use a PC that doesn’t
5 Dedicate a Logic power supply to the Centroid CNC control card Do not use the CNC control card
logic power supply to power anything else but the Centroid CNC control card Common mistakes are
using the control card logic power supply to power relays contactors solenoids etc Do not do this
Use a separate power supply to run all the other items in the CNC control system
6 Check power supply connections Verify that the connections between the logic power supply and
Centroid CNC control card are crimped properly We have seen in the past that a poor crimp in these
wires can cause random 452 errors
Technical bulletins\TB270\TB270 Solving CNCPC to MPU Communication Errors Rev15 odt 1 2 26
TB270 rev15 – Solving CNCPC to MPU Communication Errors
Discussions
Windows Ping Test
The Windows Ping Test is a great test to confirm basic Ethernet connection from the CNCPC to the
Centroid CNC controller card It helps you quickly determine if there are any “big” connections issues
between the CNCPC and the controller card It however is not a definitive test Just because the ping
test reports good results does not mean the CNC system is free of communication errors The ping
test really just confirms at that moment that the two Ethernet ports are connected and communicating
CNCPC Communication errors can and do sometimes only occur when noise electromagnetic
energy is introduced into the system or some software decides to interrupt the communication for
some reason
Communications Stress Test
The Communications Stress Test sends packages between the Motion Control and the PC It is built
into CNC12 and can be run on command to test your communication between the Control and PC To
run it select F2 Load from the Main Menu then navigate to the ncfiles directory and select
com_stress_test cnc Press Cycle Start and wait for the test to complete If the Communications
Stress Test fails follow the above steps until it passes
Acorn Power On
On very rare occasions it has been observed to make a difference whether the Acorn is turned on
before or after the CNCPC As an additional troubleshooting step it’s recommended to try turning the
Acorn on before the CNCPC and after the CNCPC to see if it makes any difference
Technical bulletins\TB270\TB270 Solving CNCPC to MPU Communication Errors Rev15 odt 1 2 26
TB270 rev15 – Solving CNCPC to MPU Communication Errors
Intermittent Communication Errors
Intermittent communication errors often show themselves when the CNCPC is being heavily taxed
one such scenario is when there is a very short vector G code program being run with Centroid CNC
G code Smoothing active While the Centroid system does NOT rely on the Windows PC CPU for
Motion control commands going to the axes motors when the Centroid G code smoothing feature is
active the Windows PC CPU is utilized to Pre process the G code program on the fly it loft arcs thru
all the short vectors of the G code program to produce significantly smoother machine tool motion
The G code smoothing feature passes a lot of data back and forth from from the CNCPC to the
Centroid CNC controller card while running the job so all the details in this document need to be right
for the best CNC machine tool performance when using this feature
*Windows Firewall Ethernet Switches Shielded Bulk Head Connectors Laptops
*All of these items can be used in conjunction with the Centroid CNC Controller but add an additional
layer of complexity by introducing a number of possible communication issues Avoid adding
complications to the system when first setting up the CNC system OR when solving communications
errors Eliminate these items to get to the point where there is good solid communication between the
CNCPC and the Centroid controller Then and only then if you really want to reintroduce these items
into the system one at a time
Understanding Communication Errors
Two types of communication errors
1 Complete shut down of communication between the MPU Centroid CNC control card such as the
Acorn Oak Allin1DC or MPU11 and the CNCPC
This type of error results in Error Message “452 Ethernet Communication Error CNCPC to controller
See Tech Bulletin 270" which appears in the main screen message box
The 452 com error is the most obvious and easiest to solve Since it is a WORKS or DOESN'T
WORK type error message
2 The Second types of Communication errors are Ethernet Packet Loss or Delay and they are more
subtle these errors are typically caused by not using a shielded ethernet cable
Looking at the Error Logs you will see error messages like this
944 MPU requested resend # 1783
945 PC requested resend # 31
946 PC resending # 120279
947 PC received data out of order # 13
948 Packet error #12
Technical bulletins\TB270\TB270 Solving CNCPC to MPU Communication Errors Rev15 odt 1 2 26
TB270 rev15 – Solving CNCPC to MPU Communication Errors
Communication error message records can be seen in the error log found in the CNC12 Utility menu
F7 Utility F9 Logs F1 Errors and same information can be found in a report zip file look in the
urf zip folder for the text file “msg_log txt”
When these types of Ethernet communication errors happen they are recorded in the error log but not
displayed on the CNC12 main screen dialog box Note Starting with CNC12 version v4 66 Acorn
and v4 22 Oak/Allin1DC/MPU11 when a certain number of these types of errors are recorded within
an hour this message will be pushed to the CNC12 main screen dialog box
“ Communication Errors Detected See TB 270”
Depending on the frequency of communication errors 944 945 946 947 948 and how the CNC control
is being used can result in puzzling hesitations in operation of the CNC control or be completely
unnoticeable by the operator In either case these errors should be eliminated following the guidance
above for good CNC control operation
Centroid Mini CNCPC Network Ports
15 Mini CNCPC’s are shipped with their network ports pre configured and labeled The port labeled
CNC is configured to work with your CNC Controller The port labeled NET is configured to be
connected to your network
Technical bulletins\TB270\TB270 Solving CNCPC to MPU Communication Errors Rev15 odt 1 2 26