Why does the counter display Error +580 "No Valid External Timebase"?

Error +580 is an indication that the external time base reference was temporarily lost while a measurement was in progress. The 53200A counters check for the presence/loss of the reference (internal or external) during the measurement. If the reference is lost, the reading that is in progress at that time is invalid. Thus, the message is generated to notify the customer that their data contains invalid readings. If the 53230A counter is not making a measurement when the reference is removed or lost, no error is reported.

The previous generation 531xxA counters check the reference at the beginning and end of a measurement, not during the measurement. If the reference is lost and restored during the measurement, the measurement is invalid. Although no error is reported by the 531xxA counters, neither is the customer made aware that their data contains invalid reading(s).