Hello,
I have one problem with robot IRB 120 with controller IRC5 compact. One day, I disconnected all cables on the controller and robot. After a few days (maybe one week), I connected all cables and I turned robot. Then, on the flexpendant is this error message:
38103, Lost communication with the SMB:
Description
The communication has been lost between the axis computer and the
serial measurement board on measurement link
1 in Drive Module 1.
Consequences
The system goes to status SYS HALT and loses its calibration
information.
Probable causes
This may be caused by bad connections or cables (screening),
especially if non-ABB cables are used for external axes. Possible
causes are also faulty serial measurement board or axis computer.
Recommended actions
1) Reset the robot's revolution counters as detailed in the robot Product
Manual.
2) Make sure the cable between serial measurement board and axis
computer is connected correctly, and that it meets the specification set
by ABB.
3) Make sure the cable screen is correctly connected at both ends.
4) Make sure no extreme levels of electromagnetic interference are
emitted close to the robot cabling.
5) Make sure the serial measurement board and axis computer are fully
functional. Replace any faulty unit.
How to solve this problem, please? 
Thanks for your response and sorry for my english.
