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'Enabled' function on expansion modules

Kevin A 2 weeks ago in IQANdesign updated by Gustav Widén (System support) 1 week ago 4

When the 'enabled' function is false it will disable all channels and use error values. When using this functional can we then disconnect the bus and not get any errors? When using this function does it become effectively 'optional' and not required as part of the complete system?


We have a customer that wants a remote analogue joystick thats not always connected to the system, we have a XC21 module that will take these signals from the joystick and send them on the bus only when the bus is connected. We want to avoid non contact with XC21 module errors flagging in the system.

Also if the 'optional' XC21 module and joystick are powered by a battery that's completely isolated from the master module (dont share the same ground) will comms be OK?

This second question is more hardware-related. CAN bus is able to tolerate some level of voltage differences between the module grounds. 

But it is very difficult for you to control how high this difference in ground voltage potential will be. When modules on the same bus have different ground levels, you are likely to see intermittent problems with the communication, and in extreme cases damage. Also see No contact and Critical CAN bus error / Knowledge base / IQAN

Yes, using the property Enabled on expansion modules is a good way of handling options. 

All channels on the expansion will get status Disabled and value Error value in the application.