HP 81101A Reference Manual

Also see for 81101A: Quick start guide

20General Programming AspectsStatus ModelCondition RegisterA condition register contains the current status of the hardware andfirmware. It is continuously updated and is not latched or buffered. Youcan only read condition registers. If there is no command to read thecondition register of a particular status group, then it is simply invisibleto you.Transition FiltersTransition filters are used to detect changes of state in the conditionregister and set the corresponding bit in the event register. You can settransition filter bits to detect positive transitions (PTR), negativetransitions (NTR) or both. Transition filters are therefore read/writeregisters. They are unaffected by *CLS.Event RegisterAn event register latches transition events from the condition register asspecified by the transition filters or records status events. Querying(reading) the event register clears it, as does the *CLS command. There isno buffering, so while a bit is set, subsequent transition events are notrecorded. Event registers are read only.ORHardwareand FirmwareconditionConditionRegisterTransitionFiltersEventRegisterEnableRegister1010PTR NTRSummary BitLatched