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cpr>Mab at 11:11, 26 June 2025

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CAN bus communication errors occur when communication between axis/IO modules and the embedded control is interrupted. This may be okay in some situtaions, may hint for a configuration issue or be caused by a defect.

The following sections explain these errors and what you can try to fix them.

= Bus Dead =
Bus dead happens if no module responds to the robot control. This is a serious issue, usually hinting to a defect.

The robot control tries to connect to the bus up to 5 times, then closes the bus connection. This means that there is no way to try loading [[Firmware Parameter Configuration|firmware parameters]] or to connect using [[Module Control]] if this error is shown.

== Troubleshooting ==
Important: Turn off the power to the cabinet before changing any wiring or modules.
# Do the green LEDs at the modules light up? If not the 5V supply coming from the embedded control module (wide module with a fan on top) does not provide voltage, check the wiring. Check wiring from the 5-pin connector at the embedded control to the modules (5 pin connector at the rail right next to the first module).
# Try starting the control cabinet with e-stop pushed and keep it pushed.
## If the error disappears try to load the [[Firmware Parameter Configuration|firmware parameters]] and check whether the motor currents are set too high.
## If the motor currents are normal and the error appears again when you release the e-stop there likely is a defect in one of the modules or the motors.
## Remove all modules from the rail, keep a single module connected. Start the control. If it shows Module dead instead of bus dead there is communication to this module and it likely is okay. Test each module separately to find the culprit.
## If all modules seem okay individually reassemble all modules and do the test again, with only one module removed at a time.

= Module Dead =
Module dead means that one or more modules (but not all of them) is not responding to the robot control. This may occur if a module failed, is missing or its CAN ID is misconfigured.

Immediately after startup or after adding a new module "module dead" may be okay, it should change to another error like "communication watchdog" quickly.

== Troubleshooting ==
# Did you add a new IO module or external axis in the configuration? [[CAN ID|If so check whether CAN ID you entered matches the yellow selector wheel at the module]].
# If you removed a module from the control cabinet replace it with a new one or remove it from the configuration.
# Try starting the cabinet with e-stop pushed. If the module communicates again load the [[Firmware Parameter Configuration|firmware parameters]] and check whether the motor currents are set too high.
# Replace the module.

= Communication Watchdog =
Communication watchdog is the module-side counterpart to "Module Dead" - it means that the module did not receive any message from the robot control within a certain time.

== Troubleshooting ==
This error is to be expected after startup since the modules start faster than the robot control software. Simply enable the motors.

It is also expected after loading firmware parameters or using Module Control. These operations intentionally disrupt communication. Re-enable the motors.

It should not occur during normal operation.
* Check the wiring
* Make sure you are not running any performance heavy [[Apps for the Robot Control|applications]] on the robot control
* [[Support Routes|Contact support]] and send us the log files.

[[Category:TinyCtrl]][[Category:Troubleshooting]]

CAN Bus Communication Errors - Revision history

OLT: 1 revision imported

cpr>Mab at 11:11, 26 June 2025