External Control Mode - Hamamatsu Photonics C8484-16C Instruction Manual

9-4-2

EXTERNAL CONTROL MODE

The external trigger pulse polarity is selected from <N (Negative) low-level active/P (Positive)
high-level active> and is input via the timing I/O connector (TIMING I/O) on the rear panel.
The external trigger pulse is at TTL level (Termination is 680 Ω).
The cycle is active for a minimum of 1 μs, and the repeat must match the selected mode.
Note
• Images are not output correctly if the pulse input is shorter than 1 μs.
The following text describes the External Control mode with the external trigger pulse polarity set
to N (Negative). If P (Positive) is selected, the rise and fall of each pulse is reversed (inverted),
with the LO interval becoming the HI interval.
Descriptions enclosed in brackets ({ }) indicate cases where P (Positive) is selected.
9-4-2-1 Exposure time setting: Internal setting
Exposure begins within 2.2 μs from the fall {rise} of the external trigger pulse, the exposure is
made using the time set with the EST n command, and readout follows. After readout, the
system waits for the external trigger pulse to fall {rise} again. The exposure time (electronic
shutter time) is set with the EST n command. This setting is made in units of one horizontal
scan cycle. The repeat cycle is controlled by the external control pulse's repeat cycle.
Note
• Set the external control pulse's repeat cycle so that it is longer than the minimum cycle.
(1) Normal readout
Exposure and normal readout repeat according to the sequence set internally.
Command
External control pulse :
Scan mode
Exposure time
1V (vertical)
Setting count
Minimum Repeat cycle can be calculated using the formula below.
Minimum repeat cycle = 83.8 ms (readout time) + set exposure time
Exposure time can be calculated using the formula below.
Exposure time = 14.5 µs + (n-1) × 79.3 µs
External trigger pulse
CCD exposure
Electrical shutter signal
Readout signal
from CCD chip
Digital data output
: AMD E (External control mode)
ATP N {ATP P}
: SMD N ( Normal)
: EMD E, EST n (Internal setting)
: 79.3 µs
: 1H to 12 930H (14.5 µs to 1.025 s)
C8484-16C Instruction manual Ver.1.5
(n = 1 to 12 930)
min. 1 µs
Exposure time = EST n
max. 2.2 µs
Readout period
23