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10.0 Smart AEC Mode
In Smart AEC Mode (S-MAC) the exposure is split into multiple parts. All
parts of the exposure are required to use the same filament and HSS speed, but
the kV / mA / exposure time are allowed to change between parts of the
exposure. The Prep, Exposure Control, X-Ray On (status), and AEC signals,
along with the serial command port are all involved with Smart AEC mode. The
sequence of events for doing a Smart AEC exposure is as follows:
1. The host sends the required commands to set up the exposure. These
are HSS Speed, Filament, kV, mA, and exposure time for 3 point
mode, Filament, kV and mAs for 2 point mode, or kV, mAs, mA,
Filament and HSS Speed in mAs+mA mode. (Note that in, 2 point
mode HSS Speed is automatically set to Fast).
2. The host sets Prep “On”. The unit will go into the Boost / Preheat
phase on the filament. (See Note 1).
3. The host sets exposure control ON and AEC control ON to enable X-
Rays. AEC may be set ON before or simultaneous with exposure
control ON.
4. The unit will turn High voltage ON. High voltage will remain ON until
the programmed exposure time has elapsed. The host should monitor
the X-Ray On status.
5. After the X-Ray On status transitions from ON to OFF the Host should
set the AEC control to the X-Ray disabled state (Low). The host must
also leave the Prep and exposure control signals ON during this time.
6. The host must now send the settings for the next part of the exposure
over the serial interface. Any combination of kV, mA, exposure time if
in 3-point mode, or kV and mAs if in 2-point mode may be changed.
HSS Speed and Filament may not be changed. Note that the host is
required to send a new set of kV/mA/time or mAs control settings, even
if they are the same as the previous settings.
7. The host must wait a minimum of 20 milliseconds after the end of the
last command for the PMX unit to process the commands. By the end
of the 20 millisecond period the next part of the exposure will be set up
and a new value of preheat current applied to the filament. (See Note
2).
8. The host sets the AEC signal High to indicate the next part of the
exposure can begin.
9. The PMX unit will turn High voltage ON. High voltage will remain ON
until the programmed exposure time has elapsed. The host should
monitor the X-Ray On status.
10. When the X-Ray transitions to OFF the host should again set AEC
signal low (X-Ray disabled state).
11. If the user requires more exposures, steps 6 – 10 can be repeated as
many times as required, the only limitation being the total sequence
must be less than the 30 second “Time in Prep” limit.
