User Manual DDS200 Digital Demodulation System 070-9952-00

Remote ControlCONDition register. The CONDition register is directly written to by the hardwareor the summary bit of the next lower register. Its contents reflects the currentdevice status. This register can be read but not written or cleared. Reading theregister does not change its contents.PTRansition register. The Positive TRansition register acts as a transition filter.Upon transition of a bit of the CONDition register from 0 to 1, the associatedPTR bit decides whether the EVENt bit will be set to 1.PTR bit = 1: the EVENt bit is set.PTR bit = 0: the EVENt bit is not set.This register can be written and read. Reading the register does not change itscontents.NTRansition register. The Negative TRansition register also acts as a transitionfilter. Upon transition of a bit of the CONDition register from 1 to 0, theassociated NTR bit decides whether the EVENt bit is set to 1.NTR bit = 1: the EVENt bit is set.NTR bit = 0: the EVENt bit is not set.This register can be written and read. Reading the register does not change itscontents.With the aid of these two transition filter registers, the user can define the statuschange of the CONDition register (none, 0 to 1, 1 to 0 or both) that is to bereported in the EVENt register.EVENt register. The EVENt register reports whether an event has occurred sinceits last reading; it is the memory of the CONDition register. It only registersevents that have been reported by the transition filters. The EVENt register iscontinuously updated by the instrument. It can only be read by the user. Readingthis register clears its contents. This register is frequently referred to as theoverall register.ENABle register. The ENABle register determines whether the EVENt bit affectsthe summary bit (refer to Summary bit on page 3–21). Each bit of the EVENtregister is ANDed (symbol ‘&’) with the associated ENABle bit. The events ofall logical operations of this register are ORed (symbol ‘+’) and passed on to thesummary bit.ENAB bit = 0: the associated EVENt bit does not affect the summary bit.ENAB bit = 1: if the associated EVENt is “1”, the summary bit is alsoset to “1”.3–20 DDS200 Digital Demodulation System User Manual