The value shown for the 'Total Error Count' does not match the summation of the Cable A and Cable B errors.
If you run MBPStat and look at the 'Network Statistics' page, there is a status counter for “No response received” (See below) which is an indication of that MB+ device trying to talk to another device not on the network to see if it has been added to the network. This is what allows new devices to be added to the token ring passing algorithm and start communicating on the network. The 'Total Error Count' would include the errors from both cable A and B plus the number of 'No responses received'.
