Programming instructions

20
General Programming Aspects
Status Model
Condition Register
A condition register contains the current status of the hardware and
firmware. It is continuously updated and is not latched or buffered. You
can only read condition registers. If there is no command to read the
condition register of a particular status group, then it is simply invisible
to you.
Transition Filters
Transition filters are used to detect changes of state in the condition
register and set the corresponding bit in the event register. You can set
transition filter bits to detect positive transitions (PTR), negative
transitions (NTR) or both. Transition filters are therefore read/write
registers. They are unaffected by *CLS.
Event Register
An event register latches transition events from the condition register as
specified by the transition filters or records status events. Querying
(reading) the event register clears it, as does the *CLS command. There is
no buffering, so while a bit is set, subsequent transition events are not
recorded. Event registers are read only.
OR
Hardware
and Firmware
condition
C
on
di
t
i
on
Register
T
rans
i
t
i
on
Filters
E
vent
Register
E
na
bl
e
Register
1
0
1
0
PTR NTR
Summary Bit
Latched